Messages in this thread | | | Subject | Re: CPU_BIG_ENDIAN in generic code (was: Re: [PATCH v3 3/7] arch/sparc: Define config parameter CPU_BIG_ENDIAN) | From | Babu Moger <> | Date | Wed, 24 May 2017 12:03:38 -0500 |
| |
On 5/24/2017 10:09 AM, Arnd Bergmann wrote: > On Wed, May 24, 2017 at 4:45 PM, Babu Moger <babu.moger@oracle.com> wrote: >> On 5/24/2017 5:18 AM, Arnd Bergmann wrote: >>> On Wed, May 24, 2017 at 11:59 AM, Geert Uytterhoeven >>> <geert@linux-m68k.org> wrote: >>>> On Tue, May 23, 2017 at 11:45 PM, Babu Moger <babu.moger@oracle.com> >>>> wrote: >>>> include/asm-generic/qrwlock.h is also generic, but depends on the >>>> architecture to select ARCH_USE_QUEUED_RWLOCKS, which only very few do >>>> (x86, and now sparc). >>>> >>>> I guess the time is ripe for adding (both) symbols to all architectures? >>> Good idea. I think we can do most of this by adding a few lines to >>> arch/Kconfig: >>> >>> config CPU_BIG_ENDIAN >>> bool >>> >>> config CPU_LITTLE_ENDIAN >>> def_bool !CPU_BIG_ENDIAN >> I noticed that even x86 does not define CPU_LITTLE_ENDIAN. Strange. > There is no architecture-independent code that tests for > CONFIG_CPU_LITTLE_ENDIAN, unlike CONFIG_CPU_BIG_ENDIAN, > so that's not very suprising.
Ok. Thanks >> With this code all the architecture will default to >> CONFIG_CPU_LITTLE_ENDIAN. > What I meant is that we have to 'select CPU_BIG_ENDIAN' on all architectures > that actually are big-endian: Ok. Sure. > > These are all configurable: > $ git grep -l linux/byteorder/big_endian.h | xargs grep -l > linux/byteorder/little_endian.h > arch/arc/include/uapi/asm/byteorder.h > arch/arm/include/uapi/asm/byteorder.h > arch/arm64/include/uapi/asm/byteorder.h > arch/c6x/include/uapi/asm/byteorder.h > arch/m32r/include/uapi/asm/byteorder.h > arch/microblaze/include/uapi/asm/byteorder.h > arch/mips/include/uapi/asm/byteorder.h > arch/powerpc/include/uapi/asm/byteorder.h > arch/sh/include/uapi/asm/byteorder.h > arch/tile/include/uapi/asm/byteorder.h > > These are always big-endian: > $ git grep -l linux/byteorder/big_endian.h | xargs grep -L > linux/byteorder/little_endian.h > arch/avr32/include/uapi/asm/byteorder.h > arch/frv/include/uapi/asm/byteorder.h > arch/m68k/include/uapi/asm/byteorder.h > arch/openrisc/include/uapi/asm/byteorder.h > arch/parisc/include/uapi/asm/byteorder.h > arch/s390/include/uapi/asm/byteorder.h > arch/sparc/include/uapi/asm/byteorder.h > > And these are always little-endian: > arch/alpha/include/uapi/asm/byteorder.h > arch/blackfin/include/uapi/asm/byteorder.h > arch/cris/include/uapi/asm/byteorder.h > arch/hexagon/include/uapi/asm/byteorder.h > arch/ia64/include/uapi/asm/byteorder.h > arch/metag/include/uapi/asm/byteorder.h > arch/mn10300/include/uapi/asm/byteorder.h > arch/score/include/uapi/asm/byteorder.h > arch/unicore32/include/uapi/asm/byteorder.h > arch/x86/include/uapi/asm/byteorder.h > > So if we 'select CPU_BIG_ENDIAN' from avr32, frv, m68k, openrisc, parisc, > s390 and sparc, this covers all the fixed-endian architectures, and the > other ones are those that already have either CPU_BIG_ENDIAN > as a 'bool' option, or both as a 'choice'. Ok. Great details. I think I have all the details required for the first version. Will post it soon. Thanks
>> I can make it as a separate patch. But I can only test SPARC and little bit >> of x86. Is that ok? > I think that's ok. > > Arnd
| |