diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/cpu-freq/user-guide.txt | 6 | ||||
| -rw-r--r-- | Documentation/credentials.txt | 582 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | Documentation/scheduler/sched-design-CFS.txt | 21 | ||||
| -rw-r--r-- | Documentation/sh/kgdb.txt | 179 | ||||
| -rw-r--r-- | Documentation/sound/alsa/ALSA-Configuration.txt | 330 | ||||
| -rw-r--r-- | Documentation/sound/alsa/HD-Audio-Models.txt | 348 | ||||
| -rw-r--r-- | Documentation/sound/alsa/HD-Audio.txt | 577 | ||||
| -rw-r--r-- | Documentation/sound/alsa/Procfile.txt | 10 | ||||
| -rw-r--r-- | Documentation/sound/alsa/soc/machine.txt | 8 |
10 files changed, 1564 insertions, 501 deletions
diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt index 4f3f3840320..e3443ddcfb8 100644 --- a/Documentation/cpu-freq/user-guide.txt +++ b/Documentation/cpu-freq/user-guide.txt @@ -93,10 +93,8 @@ Several "PowerBook" and "iBook2" notebooks are supported. 1.5 SuperH ---------- -The following SuperH processors are supported by cpufreq: - -SH-3 -SH-4 +All SuperH processors supporting rate rounding through the clock +framework are supported by cpufreq. 1.6 Blackfin ------------ diff --git a/Documentation/credentials.txt b/Documentation/credentials.txt new file mode 100644 index 00000000000..df03169782e --- /dev/null +++ b/Documentation/credentials.txt @@ -0,0 +1,582 @@ + ==================== + CREDENTIALS IN LINUX + ==================== + +By: David Howells <dhowells@redhat.com> + +Contents: + + (*) Overview. + + (*) Types of credentials. + + (*) File markings. + + (*) Task credentials. + + - Immutable credentials. + - Accessing task credentials. + - Accessing another task's credentials. + - Altering credentials. + - Managing credentials. + + (*) Open file credentials. + + (*) Overriding the VFS's use of credentials. + + +======== +OVERVIEW +======== + +There are several parts to the security check performed by Linux when one +object acts upon another: + + (1) Objects. + + Objects are things in the system that may be acted upon directly by + userspace programs. Linux has a variety of actionable objects, including: + + - Tasks + - Files/inodes + - Sockets + - Message queues + - Shared memory segments + - Semaphores + - Keys + + As a part of the description of all these objects there is a set of + credentials. What's in the set depends on the type of object. + + (2) Object ownership. + + Amongst the credentials of most objects, there will be a subset that + indicates the ownership of that object. This is used for resource + accounting and limitation (disk quotas and task rlimits for example). + + In a standard UNIX filesystem, for instance, this will be defined by the + UID marked on the inode. + + (3) The objective context. + + Also amongst the credentials of those objects, there will be a subset that + indicates the 'objective context' of that object. This may or may not be + the same set as in (2) - in standard UNIX files, for instance, this is the + defined by the UID and the GID marked on the inode. + + The objective context is used as part of the security calculation that is + carried out when an object is acted upon. + + (4) Subjects. + + A subject is an object that is acting upon another object. + + Most of the objects in the system are inactive: they don't act on other + objects within the system. Processes/tasks are the obvious exception: + they do stuff; they access and manipulate things. + + Objects other than tasks may under some circumstances also be subjects. + For instance an open file may send SIGIO to a task using the UID and EUID + given to it by a task that called fcntl(F_SETOWN) upon it. In this case, + the file struct will have a subjective context too. + + (5) The subjective context. + + A subject has an additional interpretation of its credentials. A subset + of its credentials forms the 'subjective context'. The subjective context + is used as part of the security calculation that is carried out when a + subject acts. + + A Linux task, for example, has the FSUID, FSGID and the supplementary + group list for when it is acting upon a file - which are quite separate + from the real UID and GID that normally form the objective context of the + task. + + (6) Actions. + + Linux has a number of actions available that a subject may perform upon an + object. The set of actions available depends on the nature of the subject + and the object. + + Actions include reading, writing, creating and deleting files; forking or + signalling and tracing tasks. + + (7) Rules, access control lists and security calculations. + + When a subject acts upon an object, a security calculation is made. This + involves taking the subjective context, the objective context and the + action, and searching one or more sets of rules to see whether the subject + is granted or denied permission to act in the desired manner on the + object, given those contexts. + + There are two main sources of rules: + + (a) Discretionary access control (DAC): + + Sometimes the object will include sets of rules as part of its + description. This is an 'Access Control List' or 'ACL'. A Linux + file may supply more than one ACL. + + A traditional UNIX file, for example, includes a permissions mask that + is an abbreviated ACL with three fixed classes of subject ('user', + 'group' and 'other'), each of which may be granted certain privileges + ('read', 'write' and 'execute' - whatever those map to for the object + in question). UNIX file permissions do not allow the arbitrary + specification of subjects, however, and so are of limited use. + + A Linux file might also sport a POSIX ACL. This is a list of rules + that grants various permissions to arbitrary subjects. + + (b) Mandatory access control (MAC): + + The system as a whole may have one or more sets of rules that get + applied to all subjects and objects, regardless of their source. + SELinux and Smack are examples of this. + + In the case of SELinux and Smack, each object is given a label as part + of its credentials. When an action is requested, they take the + subject label, the object label and the action and look for a rule + that says that this action is either granted or denied. + + +==================== +TYPES OF CREDENTIALS +==================== + +The Linux kernel supports the following types of credentials: + + (1) Traditional UNIX credentials. + + Real User ID + Real Group ID + + The UID and GID are carried by most, if not all, Linux objects, even if in + some cases it has to be invented (FAT or CIFS files for example, which are + derived from Windows). These (mostly) define the objective context of + that object, with tasks being slightly different in some cases. + + Effective, Saved and FS User ID + Effective, Saved and FS Group ID + Supplementary groups + + These are additional credentials used by tasks only. Usually, an + EUID/EGID/GROUPS will be used as the subjective context, and real UID/GID + will be used as the objective. For tasks, it should be noted that this is + not always true. + + (2) Capabilities. + + Set of permitted capabilities + Set of inheritable capabilities + Set of effective capabilities + Capability bounding set + + These are only carried by tasks. They indicate superior capabilities + granted piecemeal to a task that an ordinary task wouldn't otherwise have. + These are manipulated implicitly by changes to the traditional UNIX + credentials, but can also be manipulated directly by the capset() system + call. + + The permitted capabilities are those caps that the process might grant + itself to its effective or permitted sets through capset(). This + inheritable set might also be so constrained. + + The effective capabilities are the ones that a task is actually allowed to + make use of itself. + + The inheritable capabilities are the ones that may get passed across + execve(). + + The bounding set limits the capabilities that may be inherited across + execve(), especially when a binary is executed that will execute as UID 0. + + (3) Secure management flags (securebits). + + These are only carried by tasks. These govern the way the above + credentials are manipulated and inherited over certain operations such as + execve(). They aren't used directly as objective or subjective + credentials. + + (4) Keys and keyrings. + + These are only carried by tasks. They carry and cache security tokens + that don't fit into the other standard UNIX credentials. They are for + making such things as network filesystem keys available to the file + accesses performed by processes, without the necessity of ordinary + programs having to know about security details involved. + + Keyrings are a special type of key. They carry sets of other keys and can + be searched for the desired key. Each process may subscribe to a number + of keyrings: + + Per-thread keying + Per-process keyring + Per-session keyring + + When a process accesses a key, if not already present, it will normally be + cached on one of these keyrings for future accesses to find. + + For more information on using keys, see Documentation/keys.txt. + + (5) LSM + + The Linux Security Module allows extra controls to be placed over the + operations that a task may do. Currently Linux supports two main + alternate LSM options: SELinux and Smack. + + Both work by labelling the objects in a system and then applying sets of + rules (policies) that say what operations a task with one label may do to + an object with another label. + + (6) AF_KEY + + This is a socket-based approach to credential management for networking + stacks [RFC 2367]. It isn't discussed by this document as it doesn't + interact directly with task and file credentials; rather it keeps system + level credentials. + + +When a file is opened, part of the opening task's subjective context is +recorded in the file struct created. This allows operations using that file +struct to use those credentials instead of the subjective context of the task +that issued the operation. An example of this would be a file opened on a +network filesystem where the credentials of the opened file should be presented +to the server, regardless of who is actually doing a read or a write upon it. + + +============= +FILE MARKINGS +============= + +Files on disk or obtained over the network may have annotations that form the +objective security context of that file. Depending on the type of filesystem, +this may include one or more of the following: + + (*) UNIX UID, GID, mode; + + (*) Windows user ID; + + (*) Access control list; + + (*) LSM security label; + + (*) UNIX exec privilege escalation bits (SUID/SGID); + + (*) File capabilities exec privilege escalation bits. + +These are compared to the task's subjective security context, and certain +operations allowed or disallowed as a result. In the case of execve(), the +privilege escalation bits come into play, and may allow the resulting process +extra privileges, based on the annotations on the executable file. + + +================ +TASK CREDENTIALS +================ + +In Linux, all of a task's credentials are held in (uid, gid) or through +(groups, keys, LSM security) a refcounted structure of type 'struct cred'. +Each task points to its credentials by a pointer called 'cred' in its +task_struct. + +Once a set of credentials has been prepared and committed, it may not be +changed, barring the following exceptions: + + (1) its reference count may be changed; + + (2) the reference count on the group_info struct it points to may be changed; + + (3) the reference count on the security data it points to may be changed; + + (4) the reference count on any keyrings it points to may be changed; + + (5) any keyrings it points to may be revoked, expired or have their security + attributes changed; and + + (6) the contents of any keyrings to which it points may be changed (the whole + point of keyrings being a shared set of credentials, modifiable by anyone + with appropriate access). + +To alter anything in the cred struct, the copy-and-replace principle must be +adhered to. First take a copy, then alter the copy and then use RCU to change +the task pointer to make it point to the new copy. There are wrappers to aid +with this (see below). + +A task may only alter its _own_ credentials; it is no longer permitted for a +task to alter another's credentials. This means the capset() system call is no +longer permitted to take any PID other than the one of the current process. +Also keyctl_instantiate() and keyctl_negate() functions no longer permit +attachment to process-specific keyrings in the requesting process as the +instantiating process may need to create them. + + +IMMUTABLE CREDENTIALS +--------------------- + +Once a set of credentials has been made public (by calling commit_creds() for +example), it must be considered immutable, barring two exceptions: + + (1) The reference count may be altered. + + (2) Whilst the keyring subscriptions of a set of credentials may not be + changed, the keyrings subscribed to may have their contents altered. + +To catch accidental credential alteration at compile time, struct task_struct +has _const_ pointers to its credential sets, as does struct file. Furthermore, +certain functions such as get_cred() and put_cred() operate on const pointers, +thus rendering casts unnecessary, but require to temporarily ditch the const +qualification to be able to alter the reference count. + + +ACCESSING TASK CREDENTIALS +-------------------------- + +A task being able to alter only its own credentials permits the current process +to read or replace its own credentials without the need for any form of locking +- which simplifies things greatly. It can just call: + + const struct cred *current_cred() + +to get a pointer to its credentials structure, and it doesn't have to release +it afterwards. + +There are convenience wrappers for retrieving specific aspects of a task's +credentials (the value is simply returned in each case): + + uid_t current_uid(void) Current's real UID + gid_t current_gid(void) Current's real GID + uid_t current_euid(void) Current's effective UID + gid_t current_egid(void) Current's effective GID + uid_t current_fsuid(void) Current's file access UID + gid_t current_fsgid(void) Current's file access GID + kernel_cap_t current_cap(void) Current's effective capabilities + void *current_security(void) Current's LSM security pointer + struct user_struct *current_user(void) Current's user account + +There are also convenience wrappers for retrieving specific associated pairs of +a task's credentials: + + void current_uid_gid(uid_t *, gid_t *); + void current_euid_egid(uid_t *, gid_t *); + void current_fsuid_fsgid(uid_t *, gid_t *); + +which return these pairs of values through their arguments after retrieving +them from the current task's credentials. + + +In addition, there is a function for obtaining a reference on the current +process's current set of credentials: + + const struct cred *get_current_cred(void); + +and functions for getting references to one of the credentials that don't +actually live in struct cred: + + struct user_struct *get_current_user(void); + struct group_info *get_current_groups(void); + +which get references to the current process's user accounting structure and +supplementary groups list respectively. + +Once a reference has been obtained, it must be released with put_cred(), +free_uid() or put_group_info() as appropriate. + + +ACCESSING ANOTHER TASK'S CREDENTIALS +------------------------------------ + +Whilst a task may access its own credentials without the need for locking, the +same is not true of a task wanting to access another task's credentials. It +must use the RCU read lock and rcu_dereference(). + +The rcu_dereference() is wrapped by: + + const struct cred *__task_cred(struct task_struct *task); + +This should be used inside the RCU read lock, as in the following example: + + void foo(struct task_struct *t, struct foo_data *f) + { + const struct cred *tcred; + ... + rcu_read_lock(); + tcred = __task_cred(t); + f->uid = tcred->uid; + f->gid = tcred->gid; + f->groups = get_group_info(tcred->groups); + rcu_read_unlock(); + ... + } + +A function need not get RCU read lock to use __task_cred() if it is holding a +spinlock at the time as this implicitly holds the RCU read lock. + +Should it be necessary to hold another task's credentials for a long period of +time, and possibly to sleep whilst doing so, then the caller should get a +reference on them using: + + const struct cred *get_task_cred(struct task_struct *task); + +This does all the RCU magic inside of it. The caller must call put_cred() on +the credentials so obtained when they're finished with. + +There are a couple of convenience functions to access bits of another task's +credentials, hiding the RCU magic from the caller: + + uid_t task_uid(task) Task's real UID + uid_t task_euid(task) Task's effective UID + +If the caller is holding a spinlock or the RCU read lock at the time anyway, +then: + + __task_cred(task)->uid + __task_cred(task)->euid + +should be used instead. Similarly, if multiple aspects of a task's credentials +need to be accessed, RCU read lock or a spinlock should be used, __task_cred() +called, the result stored in a temporary pointer and then the credential +aspects called from that before dropping the lock. This prevents the +potentially expensive RCU magic from being invoked multiple times. + +Should some other single aspect of another task's credentials need to be +accessed, then this can be used: + + task_cred_xxx(task, member) + +where 'member' is a non-pointer member of the cred struct. For instance: + + uid_t task_cred_xxx(task, suid); + +will retrieve 'struct cred::suid' from the task, doing the appropriate RCU +magic. This may not be used for pointer members as what they point to may +disappear the moment the RCU read lock is dropped. + + +ALTERING CREDENTIALS +-------------------- + +As previously mentioned, a task may only alter its own credentials, and may not +alter those of another task. This means that it doesn't need to use any +locking to alter its own credentials. + +To alter the current process's credentials, a function should first prepare a +new set of credentials by calling: + + struct cred *prepare_creds(void); + +this locks current->cred_replace_mutex and then allocates and constructs a +duplicate of the current process's credentials, returning with the mutex still +held if successful. It returns NULL if not successful (out of memory). + +The mutex prevents ptrace() from altering the ptrace state of a process whilst +security checks on credentials construction and changing is taking place as +the ptrace state may alter the outcome, particularly in the case of execve(). + +The new credentials set should be altered appropriately, and any security +checks and hooks done. Both the current and the proposed sets of credentials +are available for this purpose as current_cred() will return the current set +still at this point. + + +When the credential set is ready, it should be committed to the current process +by calling: + + int commit_creds(struct cred *new); + +This will alter various aspects of the credentials and the process, giving the +LSM a chance to do likewise, then it will use rcu_assign_pointer() to actually +commit the new credentials to current->cred, it will release +current->cred_replace_mutex to allow ptrace() to take place, and it will notify +the scheduler and others of the changes. + +This function is guaranteed to return 0, so that it can be tail-called at the +end of such functions as sys_setresuid(). + +Note that this function consumes the caller's reference to the new credentials. +The caller should _not_ call put_cred() on the new credentials afterwards. + +Furthermore, once this function has been called on a new set of credentials, +those credentials may _not_ be changed further. + + +Should the security checks fail or some other error occur after prepare_creds() +has been called, then the following function should be invoked: + + void abort_creds(struct cred *new); + +This releases the lock on current->cred_replace_mutex that prepare_creds() got +and then releases the new credentials. + + +A typical credentials alteration function would look something like this: + + int alter_suid(uid_t suid) + { + struct cred *new; + int ret; + + new = prepare_creds(); + if (!new) + return -ENOMEM; + + new->suid = suid; + ret = security_alter_suid(new); + if (ret < 0) { + abort_creds(new); + return ret; + } + + return commit_creds(new); + } + + +MANAGING CREDENTIALS +-------------------- + +There are some functions to help manage credentials: + + (*) void put_cred(const struct cred *cred); + + This releases a reference to the given set of credentials. If the + reference count reaches zero, the credentials will be scheduled for + destruction by the RCU system. + + (*) const struct cred *get_cred(const struct cred *cred); + + This gets a reference on a live set of credentials, returning a pointer to + that set of credentials. + + (*) struct cred *get_new_cred(struct cred *cred); + + This gets a reference on a set of credentials that is under construction + and is thus still mutable, returning a pointer to that set of credentials. + + +===================== +OPEN FILE CREDENTIALS +===================== + +When a new file is opened, a reference is obtained on the opening task's +credentials and this is attached to the file struct as 'f_cred' in place of +'f_uid' and 'f_gid'. Code that used to access file->f_uid and file->f_gid +should now access file->f_cred->fsuid and file->f_cred->fsgid. + +It is safe to access f_cred without the use of RCU or locking because the +pointer will not change over the lifetime of the file struct, and nor will the +contents of the cred struct pointed to, barring the exceptions listed above +(see the Task Credentials section). + + +======================================= +OVERRIDING THE VFS'S USE OF CREDENTIALS +======================================= + +Under some circumstances it is desirable to override the credentials used by +the VFS, and that can be done by calling into such as vfs_mkdir() with a +different set of credentials. This is done in the following places: + + (*) sys_faccessat(). + + (*) do_coredump(). + + (*) nfs4recover.c. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index ee5a5f9358e..2c95cae8302 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1465,6 +1465,10 @@ and is between 256 and 4096 characters. It is defined in the file instruction doesn't work correctly and not to use it. + no_file_caps Tells the kernel not to honor file capabilities. The + only way then for a file to be executed with privilege + is to be setuid root or executed by root. + nohalt [IA-64] Tells the kernel not to use the power saving function PAL_HALT_LIGHT when idle. This increases power-consumption. On the positive side, it reduces diff --git a/Documentation/scheduler/sched-design-CFS.txt b/Documentation/scheduler/sched-design-CFS.txt index eb471c7a905..8398ca4ff4e 100644 --- a/Documentation/scheduler/sched-design-CFS.txt +++ b/Documentation/scheduler/sched-design-CFS.txt @@ -273,3 +273,24 @@ task groups and modify their CPU share using the "cgroups" pseudo filesystem. # #Launch gmplayer (or your favourite movie player) # echo <movie_player_pid> > multimedia/tasks + +8. Implementation note: user namespaces + +User namespaces are intended to be hierarchical. But they are currently +only partially implemented. Each of those has ramifications for CFS. + +First, since user namespaces are hierarchical, the /sys/kernel/uids +presentation is inadequate. Eventually we will likely want to use sysfs +tagging to provide private views of /sys/kernel/uids within each user +namespace. + +Second, the hierarchical nature is intended to support completely +unprivileged use of user namespaces. So if using user groups, then +we want the users in a user namespace to be children of the user +who created it. + +That is currently unimplemented. So instead, every user in a new +user namespace will receive 1024 shares just like any user in the +initial user namespace. Note that at the moment creation of a new +user namespace requires each of CAP_SYS_ADMIN, CAP_SETUID, and +CAP_SETGID. diff --git a/Documentation/sh/kgdb.txt b/Documentation/sh/kgdb.txt deleted file mode 100644 index 05b4ba89d28..00000000000 --- a/Documentation/sh/kgdb.txt +++ /dev/null @@ -1,179 +0,0 @@ - -This file describes the configuration and behavior of KGDB for the SH -kernel. Based on a description from Henry Bell <henry.bell@st.com>, it -has been modified to account for quirks in the current implementation. - -Version -======= - -This version of KGDB was written for 2.4.xx kernels for the SH architecture. -Further documentation is available from the linux-sh project website. - - -Debugging Setup: Host -====================== - -The two machines will be connected together via a serial line - this -should be a null modem cable i.e. with a twist. - -On your DEVELOPMENT machine, go to your kernel source directory and -build the kernel, enabling KGDB support in the "kernel hacking" section. -This includes the KGDB code, and also makes the kernel be compiled with -the "-g" option set -- necessary for debugging. - -To install this new kernel, use the following installation procedure. - -Decide on which tty port you want the machines to communicate, then -cable them up back-to-back using the null modem. On the DEVELOPMENT -machine, you may wish to create an initialization file called .gdbinit -(in the kernel source directory or in your home directory) to execute -commonly-used commands at startup. - -A minimal .gdbinit might look like this: - - file vmlinux - set remotebaud 115200 - target remote /dev/ttyS0 - -Change the "target" definition so that it specifies the tty port that -you intend to use. Change the "remotebaud" definition to match the -data rate that you are going to use for the com line (115200 is the -default). - -Debugging Setup: Target -======================== - -By default, the KGDB stub will communicate with the host GDB using -ttySC1 at 115200 baud, 8 databits, no parity; these defaults can be -changed in the kernel configuration. As the kernel starts up, KGDB will -initialize so that breakpoints, kernel segfaults, and so forth will -generally enter the debugger. - -This behavior can be modified by including the "kgdb" option in the -kernel command line; this option has the general form: - - kgdb=<ttyspec>,<action> - -The <ttyspec> indicates the port to use, and can optionally specify -baud, parity and databits -- e.g. "ttySC0,9600N8" or "ttySC1,19200". - -The <action> can be "halt" or "disabled". The "halt" action enters the -debugger via a breakpoint as soon as kgdb is initialized; the "disabled" -action causes kgdb to ignore kernel segfaults and such until explicitly -entered by a breakpoint in the code or by external action (sysrq or NMI). - -(Both <ttyspec> and <action> can appear alone, w/o the separating comma.) - -For example, if you wish to debug early in kernel startup code, you -might specify the halt option: - - kgdb=halt - -Boot the TARGET machine, which will appear to hang. - -On your DEVELOPMENT machine, cd to the source directory and run the gdb -program. (This is likely to be a cross GDB which runs on your host but -is built for an SH target.) If everything is working correctly you -should see gdb print out a few lines indicating that a breakpoint has -been taken. It will actually show a line of code in the target kernel -inside the gdbstub activation code. - -NOTE: BE SURE TO TERMINATE OR SUSPEND any other host application which -may be using the same serial port (for example, a terminal emulator you -have been using to connect to the target boot code.) Otherwise, data -from the target may not all get to GDB! - -You can now use whatever gdb commands you like to set breakpoints. -Enter "continue" to start your target machine executing again. At this -point the target system will run at full speed until it encounters -your breakpoint or gets a segment violation in the kernel, or whatever. - -Serial Ports: KGDB, Console -============================ - -This version of KGDB may not gracefully handle conflict with other -drivers in the kernel using the same port. If KGDB is configured on the -same port (and with the same parameters) as the kernel console, or if -CONFIG_SH_KGDB_CONSOLE is configured, things should be fine (though in -some cases console messages may appear twice through GDB). But if the -KGDB port is not the kernel console and used by another serial driver -which assumes different serial parameters (e.g. baud rate) KGDB may not -recover. - -Also, when KGDB is entered via sysrq-g (requires CONFIG_KGDB_SYSRQ) and -the kgdb port uses the same port as the console, detaching GDB will not -restore the console to working order without the port being re-opened. - -Another serious consequence of this is that GDB currently CANNOT break -into KGDB externally (e.g. via ^C or <BREAK>); unless a breakpoint or -error is encountered, the only way to enter KGDB after the initial halt -(see above) is via NMI (CONFIG_KGDB_NMI) or sysrq-g (CONFIG_KGDB_SYSRQ). - -Code is included for the basic Hitachi Solution Engine boards to allow -the use of ttyS0 for KGDB if desired; this is less robust, but may be -useful in some cases. (This cannot be selected using the config file, -but only through the kernel command line, e.g. "kgdb=ttyS0", though the -configured defaults for baud rate etc. still apply if not overridden.) - -If gdbstub Does Not Work -======================== - -If it doesn't work, you will have to troubleshoot it. Do the easy -things first like double checking your cabling and data rates. You -might try some non-kernel based programs to see if the back-to-back -connection works properly. Just something simple like cat /etc/hosts -/dev/ttyS0 on one machine and cat /dev/ttyS0 on the other will tell you -if you can send data from one machine to the other. There is no point -in tearing out your hair in the kernel if the line doesn't work. - -If you need to debug the GDB/KGDB communication itself, the gdb commands -"set debug remote 1" and "set debug serial 1" may be useful, but be -warned: they produce a lot of output. - -Threads -======= - -Each process in a target machine is seen as a gdb thread. gdb thread related -commands (info threads, thread n) can be used. CONFIG_KGDB_THREAD must -be defined for this to work. - -In this version, kgdb reports PID_MAX (32768) as the process ID for the -idle process (pid 0), since GDB does not accept 0 as an ID. - -Detaching (exiting KGDB) -========================= - -There are two ways to resume full-speed target execution: "continue" and -"detach". With "continue", GDB inserts any specified breakpoints in the -target code and resumes execution; the target is still in "gdb mode". -If a breakpoint or other debug event (e.g. NMI) happens, the target -halts and communicates with GDB again, which is waiting for it. - -With "detach", GDB does *not* insert any breakpoints; target execution -is resumed and GDB stops communicating (does not wait for the target). -In this case, the target is no longer in "gdb mode" -- for example, -console messages no longer get sent separately to the KGDB port, or -encapsulated for GDB. If a debug event (e.g. NMI) occurs, the target -will re-enter "gdb mode" and will display this fact on the console; you -must give a new "target remote" command to gdb. - -NOTE: TO AVOID LOSSING CONSOLE MESSAGES IN CASE THE KERNEL CONSOLE AND -KGDB USING THE SAME PORT, THE TARGET WAITS FOR ANY INPUT CHARACTER ON -THE KGDB PORT AFTER A DETACH COMMAND. For example, after the detach you -could start a terminal emulator on the same host port and enter a <cr>; -however, this program must then be terminated or suspended in order to -use GBD again if KGDB is re-entered. - - -Acknowledgements -================ - -This code was mostly generated by Henry Bell <henry.bell@st.com>; -largely from KGDB by Amit S. Kale <akale@veritas.com> - extracts from -code by Glenn Engel, Jim Kingdon, David Grothe <dave@gcom.com>, Tigran -Aivazian <tigran@sco.com>, William Gatliff <bgat@open-widgets.com>, Ben -Lee, Steve Chamberlain and Benoit Miller <fulg@iname.com> are also -included. - -Jeremy Siegel -<jsiegel@mvista.com> diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 394d7d378dc..841a9365d5f 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -757,6 +757,8 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. model - force the model name position_fix - Fix DMA pointer (0 = auto, 1 = use LPIB, 2 = POSBUF) probe_mask - Bitmask to probe codecs (default = -1, meaning all slots) + probe_only - Only probing and no codec initialization (default=off); + Useful to check the initial codec status for debugging bdl_pos_adj - Specifies the DMA IRQ timing delay in samples. Passing -1 will make the driver to choose the appropriate value based on the controller chip. @@ -772,327 +774,23 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. This module supports multiple cards and autoprobe. + See Documentation/sound/alsa/HD-Audio.txt for more details about + HD-audio driver. + Each codec may have a model table for different configurations. If your machine isn't listed there, the default (usually minimal) configuration is set up. You can pass "model=<name>" option to specify a certain model in such a case. There are different - models depending on the codec chip. - - Model name Description - ---------- ----------- - ALC880 - 3stack 3-jack in back and a headphone out - 3stack-digout 3-jack in back, a HP out and a SPDIF out - 5stack 5-jack in back, 2-jack in front - 5stack-digout 5-jack in back, 2-jack in front, a SPDIF out - 6stack 6-jack in back, 2-jack in front - 6stack-digout 6-jack with a SPDIF out - w810 3-jack - z71v 3-jack (HP shared SPDIF) - asus 3-jack (ASUS Mobo) - asus-w1v ASUS W1V - asus-dig ASUS with SPDIF out - asus-dig2 ASUS with SPDIF out (using GPIO2) - uniwill 3-jack - fujitsu Fujitsu Laptops (Pi1536) - F1734 2-jack - lg LG laptop (m1 express dual) - lg-lw LG LW20/LW25 laptop - tcl TCL S700 - clevo Clevo laptops (m520G, m665n) - medion Medion Rim 2150 - test for testing/debugging purpose, almost all controls can be - adjusted. Appearing only when compiled with - $CONFIG_SND_DEBUG=y - auto auto-config reading BIOS (default) - - ALC260 - hp HP machines - hp-3013 HP machines (3013-variant) - hp-dc7600 HP DC7600 < |