The previous patches added arch support matrices for more than 40 generic kernel features
that need per architecture support.
The structure of the feature descriptions is the following:
Each feature has its own directory under Documentation/features/subsystem_name/feature_name/,
and the arch-support.txt file shows its current arch porting status.
For example, lockdep support is shown the following way:
triton:~/tip> cat Documentation/features/locking/lockdep/arch-support.txt
#
# Feature name: lockdep
# Kconfig: LOCKDEP_SUPPORT
# description: arch supports the runtime locking correctness debug facility
#
-----------------------
| arch |status|
-----------------------
| alpha: | TODO |
| arc: | ok |
| arm: | ok |
| arm64: | ok |
| avr32: | ok |
| blackfin: | ok |
| c6x: | TODO |
| cris: | TODO |
| frv: | TODO |
| h8300: | TODO |
| hexagon: | ok |
| ia64: | TODO |
| m32r: | TODO |
| m68k: | TODO |
| metag: | ok |
| microblaze: | ok |
| mips: | ok |
| mn10300: | TODO |
| nios2: | TODO |
| openrisc: | TODO |
| parisc: | TODO |
| powerpc: | ok |
| s390: | ok |
| score: | ok |
| sh: | ok |
| sparc: | ok |
| tile: | ok |
| um: | ok |
| unicore32: | ok |
| x86: | ok |
| xtensa: | ok |
-----------------------
For generic kernel features that need architecture support, the
arch-support.txt file in each feature directory shows the arch
support matrix, for all upstream Linux architectures.
The meaning of entries in the tables is:
| ok | # feature supported by the architecture
|TODO| # feature not yet supported by the architecture
| .. | # feature cannot be supported by the hardware
This directory structure can be used in the future to add other
files - such as porting guides, testing description, etc.
The Documentation/features/ hierarchy may also include generic
kernel features that works on every architecture, in that case
the arch-support.txt file will list every architecture as
supported.
To list an architecture's unsupported features, just do something
like:
triton:~/tip> git grep -lE 'x86.*TODO' Documentation/features/*/*/arch-support.txt
Documentation/features/lib/strncasecmp/arch-support.txt
Documentation/features/time/arch-tick-broadcast/arch-support.txt
which will print the list of not yet supported features.
The Documentation/features/list-arch.sh script will print the current
support matrix of one architecture:
triton:~/tip> Documentation/features/list-arch.sh
#
# Kernel feature support matrix of the 'x86' architecture:
#
core/ BPF-JIT : ok | HAVE_BPF_JIT # arch supports BPF JIT optimizations
core/ generic-idle-thread : ok | GENERIC_SMP_IDLE_THREAD # arch makes use of the generic SMP idle thread facility
core/ jump-labels : ok | HAVE_ARCH_JUMP_LABEL # arch supports live patched, high efficiency branches
core/ tracehook : ok | HAVE_ARCH_TRACEHOOK # arch supports tracehook (ptrace) register handling APIs
debug/ gcov-profile-all : ok | ARCH_HAS_GCOV_PROFILE_ALL # arch supports whole-kernel GCOV code coverage profiling
debug/ KASAN : ok | HAVE_ARCH_KASAN # arch supports the KASAN runtime memory checker
debug/ kgdb : ok | HAVE_ARCH_KGDB # arch supports the kGDB kernel debugger
debug/ kprobes : ok | HAVE_KPROBES # arch supports live patched kernel probe
debug/ kprobes-on-ftrace : ok | HAVE_KPROBES_ON_FTRACE # arch supports combined kprobes and ftrace live patching
debug/ kretprobes : ok | HAVE_KRETPROBES # arch supports kernel function-return probes
debug/ optprobes : ok | HAVE_OPTPROBES # arch supports live patched optprobes
debug/ stackprotector : ok | HAVE_CC_STACKPROTECTOR # arch supports compiler driven stack overflow protection
debug/ uprobes : ok | ARCH_SUPPORTS_UPROBES # arch supports live patched user probes
debug/ user-ret-profiler : ok | HAVE_USER_RETURN_NOTIFIER # arch supports user-space return from system call profiler
io/ dma-api-debug : ok | HAVE_DMA_API_DEBUG # arch supports DMA debug facilities
io/ dma-contiguous : ok | HAVE_DMA_CONTIGUOUS # arch supports the DMA CMA (continuous memory allocator)
io/ dma_map_attrs : ok | HAVE_DMA_ATTRS # arch provides dma_*map*_attrs() APIs
io/ sg-chain : ok | ARCH_HAS_SG_CHAIN # arch supports chained scatter-gather lists
lib/ strncasecmp : TODO | __HAVE_ARCH_STRNCASECMP # arch provides an optimized strncasecmp() function
locking/ cmpxchg-local : ok | HAVE_CMPXCHG_LOCAL # arch supports the this_cpu_cmpxchg() API
locking/ lockdep : ok | LOCKDEP_SUPPORT # arch supports the runtime locking correctness debug facility
locking/ queued-rwlocks : ok | ARCH_USE_QUEUED_RWLOCKS # arch supports queued rwlocks
locking/ queued-spinlocks : ok | ARCH_USE_QUEUED_SPINLOCKS # arch supports queued spinlocks
locking/ rwsem-optimized : ok | Optimized asm/rwsem.h # arch provides optimized rwsem APIs
perf/ kprobes-event : ok | HAVE_REGS_AND_STACK_ACCESS_API # arch supports kprobes with perf events
perf/ perf-regs : ok | HAVE_PERF_REGS # arch supports perf events register access
perf/ perf-stackdump : ok | HAVE_PERF_USER_STACK_DUMP # arch supports perf events stack dumps
sched/ numa-balancing : ok | ARCH_SUPPORTS_NUMA_BALANCING # arch supports NUMA balancing
seccomp/ seccomp-filter : ok | HAVE_ARCH_SECCOMP_FILTER # arch supports seccomp filters
time/ arch-tick-broadcast : TODO | ARCH_HAS_TICK_BROADCAST # arch provides tick_broadcast()
time/ clockevents : ok | GENERIC_CLOCKEVENTS # arch support generic clock events
time/ context-tracking : ok | HAVE_CONTEXT_TRACKING # arch supports context tracking for NO_HZ_FULL
time/ irq-time-acct : ok | HAVE_IRQ_TIME_ACCOUNTING # arch supports precise IRQ time accounting
time/ modern-timekeeping : ok | !ARCH_USES_GETTIMEOFFSET # arch does not use arch_gettimeoffset() anymore
time/ virt-cpuacct : ok | HAVE_VIRT_CPU_ACCOUNTING # arch supports precise virtual CPU time accounting
vm/ ELF-ASLR : ok | ARCH_HAS_ELF_RANDOMIZE # arch randomizes the stack, heap and binary images of ELF binaries
vm/ huge-vmap : ok | HAVE_ARCH_HUGE_VMAP # arch supports the ioremap_pud_enabled() and ioremap_pmd_enabled() VM APIs
vm/ ioremap_prot : ok | HAVE_IOREMAP_PROT # arch has ioremap_prot()
vm/ numa-memblock : ok | HAVE_MEMBLOCK_NODE_MAP # arch supports NUMA aware memblocks
vm/ PG_uncached : ok | ARCH_USES_PG_UNCACHED # arch supports the PG_uncached page flag
vm/ pmdp_splitting_flush : ok | __HAVE_ARCH_PMDP_SPLITTING_FLUSH # arch supports the pmdp_splitting_flush() VM API
vm/ pte_special : ok | __HAVE_ARCH_PTE_SPECIAL # arch supports the pte_special()/pte_mkspecial() VM APIs
vm/ THP : ok | HAVE_ARCH_TRANSPARENT_HUGEPAGE # arch supports transparent hugepages
Cc: <linux-api@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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