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| author | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-04-19 09:23:28 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-04-19 09:23:28 -0300 |
| commit | d5aeee8cb28317ef608ecac421abc4d986d585d2 (patch) | |
| tree | 70ec8ed8891f26e5c58152ffca9924ea1c58fe3a /Documentation/CodingStyle | |
| parent | 32898a145404acbebe3256709e012c2830a2043b (diff) | |
| parent | e816b57a337ea3b755de72bec38c10c864f23015 (diff) | |
Merge tag 'v3.4-rc3' into staging/for_v3.5
* tag 'v3.4-rc3': (3755 commits)
Linux 3.4-rc3
x86-32: fix up strncpy_from_user() sign error
ARM: 7386/1: jump_label: fixup for rename to static_key
ARM: 7384/1: ThumbEE: Disable userspace TEEHBR access for !CONFIG_ARM_THUMBEE
ARM: 7382/1: mm: truncate memory banks to fit in 4GB space for classic MMU
ARM: 7359/2: smp_twd: Only wait for reprogramming on active cpus
PCI: Fix regression in pci_restore_state(), v3
SCSI: Fix error handling when no ULD is attached
ARM: OMAP: clock: cleanup CPUfreq leftovers, fix build errors
ARM: dts: remove blank interrupt-parent properties
ARM: EXYNOS: Fix Kconfig dependencies for device tree enabled machine files
do not export kernel's NULL #define to userspace
ARM: EXYNOS: Remove broken config values for touchscren for NURI board
ARM: EXYNOS: set fix xusbxti clock for NURI and Universal210 boards
ARM: EXYNOS: fix regulator name for NURI board
ARM: SAMSUNG: make SAMSUNG_PM_DEBUG select DEBUG_LL
cpufreq: OMAP: fix build errors: depends on ARCH_OMAP2PLUS
sparc64: Eliminate obsolete __handle_softirq() function
sparc64: Fix bootup crash on sun4v.
ARM: msm: Fix section mismatches in proc_comm.c
...
Diffstat (limited to 'Documentation/CodingStyle')
| -rw-r--r-- | Documentation/CodingStyle | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle index 2b90d328b3b..c58b236bbe0 100644 --- a/Documentation/CodingStyle +++ b/Documentation/CodingStyle @@ -793,6 +793,35 @@ own custom mode, or may have some other magic method for making indentation work correctly. + Chapter 19: Inline assembly + +In architecture-specific code, you may need to use inline assembly to interface +with CPU or platform functionality. Don't hesitate to do so when necessary. +However, don't use inline assembly gratuitously when C can do the job. You can +and should poke hardware from C when possible. + +Consider writing simple helper functions that wrap common bits of inline +assembly, rather than repeatedly writing them with slight variations. Remember +that inline assembly can use C parameters. + +Large, non-trivial assembly functions should go in .S files, with corresponding +C prototypes defined in C header files. The C prototypes for assembly +functions should use "asmlinkage". + +You may need to mark your asm statement as volatile, to prevent GCC from +removing it if GCC doesn't notice any side effects. You don't always need to +do so, though, and doing so unnecessarily can limit optimization. + +When writing a single inline assembly statement containing multiple +instructions, put each instruction on a separate line in a separate quoted +string, and end each string except the last with \n\t to properly indent the +next instruction in the assembly output: + + asm ("magic %reg1, #42\n\t" + "more_magic %reg2, %reg3" + : /* outputs */ : /* inputs */ : /* clobbers */); + + Appendix I: References |
