diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/filesystems/xfs.txt | 3 | ||||
| -rw-r--r-- | Documentation/powerpc/transactional_memory.txt | 27 |
2 files changed, 28 insertions, 2 deletions
diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt index 3e4b3dd1e04..83577f0232a 100644 --- a/Documentation/filesystems/xfs.txt +++ b/Documentation/filesystems/xfs.txt @@ -33,6 +33,9 @@ When mounting an XFS filesystem, the following options are accepted. removing extended attributes) the on-disk superblock feature bit field will be updated to reflect this format being in use. + CRC enabled filesystems always use the attr2 format, and so + will reject the noattr2 mount option if it is set. + barrier Enables the use of block layer write barriers for writes into the journal and unwritten extent conversion. This allows for diff --git a/Documentation/powerpc/transactional_memory.txt b/Documentation/powerpc/transactional_memory.txt index c907be41d60..dc23e58ae26 100644 --- a/Documentation/powerpc/transactional_memory.txt +++ b/Documentation/powerpc/transactional_memory.txt @@ -147,6 +147,25 @@ Example signal handler: fix_the_problem(ucp->dar); } +When in an active transaction that takes a signal, we need to be careful with +the stack. It's possible that the stack has moved back up after the tbegin. +The obvious case here is when the tbegin is called inside a function that +returns before a tend. In this case, the stack is part of the checkpointed +transactional memory state. If we write over this non transactionally or in +suspend, we are in trouble because if we get a tm abort, the program counter and +stack pointer will be back at the tbegin but our in memory stack won't be valid +anymore. + +To avoid this, when taking a signal in an active transaction, we need to use +the stack pointer from the checkpointed state, rather than the speculated +state. This ensures that the signal context (written tm suspended) will be +written below the stack required for the rollback. The transaction is aborted +becuase of the treclaim, so any memory written between the tbegin and the +signal will be rolled back anyway. + +For signals taken in non-TM or suspended mode, we use the +normal/non-checkpointed stack pointer. + Failure cause codes used by kernel ================================== @@ -155,14 +174,18 @@ These are defined in <asm/reg.h>, and distinguish different reasons why the kernel aborted a transaction: TM_CAUSE_RESCHED Thread was rescheduled. + TM_CAUSE_TLBI Software TLB invalide. TM_CAUSE_FAC_UNAV FP/VEC/VSX unavailable trap. TM_CAUSE_SYSCALL Currently unused; future syscalls that must abort transactions for consistency will use this. TM_CAUSE_SIGNAL Signal delivered. TM_CAUSE_MISC Currently unused. + TM_CAUSE_ALIGNMENT Alignment fault. + TM_CAUSE_EMULATE Emulation that touched memory. -These can be checked by the user program's abort handler as TEXASR[0:7]. - +These can be checked by the user program's abort handler as TEXASR[0:7]. If +bit 7 is set, it indicates that the error is consider persistent. For example +a TM_CAUSE_ALIGNMENT will be persistent while a TM_CAUSE_RESCHED will not.q GDB === |