diff options
| author | Yury Norov <ynorov@nvidia.com> | 2026-05-06 13:52:03 -0400 |
|---|---|---|
| committer | Yury Norov <ynorov@nvidia.com> | 2026-05-28 11:39:16 -0400 |
| commit | 00751d655ece97fe85ce9193542ee8396fe98651 (patch) | |
| tree | 4d95cb8b90000b72d4a92bbaf1c6cac29de04c2c /lib/Makefile | |
| parent | 42d9c75e8b9cae9583c228617be38ab1637fd574 (diff) | |
lib/bitrev: Introduce GENERIC_BITREVERSE
The generic bit reversal implementation is controlled by
!HAVE_ARCH_BITREVERSE. This makes it difficult for architectures to
provide a hardware-accelerated implementation while being able to
fall back to the generic version if needed.
This patch adds GENERIC_BITREVERSE, so bitreverse API is controlled by
BITREVERSE, GENERIC_BITREVERSE and HAVE_ARCH_BITREVERSE options. The
relationship between them is described as follows:
- BITREVERSE is selected by user code; it's required to generate the API;
- Architectures may select HAVE_ARCH_BITREVERSE and provide an arch
implementation in arch/$(ARCH)/include/asm/bitrev.h.
- if HAVE_ARCH_BITREVERSE isn't set, BITREVERSE selects GENERIC_BITREVERSE;
- if GENERIC_BITREVERSE is set and HAVE_ARCH_BITREVERSE is not, the kernel
provides generic implementation only, and wires bitrevXX() to it.
- if HAVE_ARCH_BITREVERSE is set and GENERIC_BITREVERSE is not, the arch
code provides __arch_bitrevXX(), and it is wired to bitrevXX();
- if both GENERIC_BITREVERSE and HAVE_ARCH_BITREVERSE are selected, the kernel
generates generic___bitrev(), but wires bitrev() to the __arch_bitrev().
The last option allows architectures to use generic___bitrev() as a
fallback option.
Drivers and core code should never select GENERIC_BITREVERSE or
HAVE_ARCH_BITREVERSE explicitly.
Architectures that require generic bitreverse API as a fallback should
explicitly enable GENERIC_BITREVERSE together with HAVE_ARCH_BITREVERSE.
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Diffstat (limited to 'lib/Makefile')
| -rw-r--r-- | lib/Makefile | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/Makefile b/lib/Makefile index f33a24bf1c19..23e07d19d01c 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -145,7 +145,7 @@ obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o obj-$(CONFIG_LIST_HARDENED) += list_debug.o obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o -obj-$(CONFIG_BITREVERSE) += bitrev.o +obj-$(CONFIG_GENERIC_BITREVERSE) += bitrev.o obj-$(CONFIG_LINEAR_RANGES) += linear_ranges.o obj-$(CONFIG_PACKING) += packing.o obj-$(CONFIG_PACKING_KUNIT_TEST) += packing_test.o |