[PATCH v4 0/2] Implement endianess swap macros for RISC-V

[Alexandre Ghiti]

Hi Ignacio,

Can you come up with a new version that only touches the riscv tree so 
that we can merge this in 6.17? Not ideal but I guess we can live with 
code duplication for now.

Thanks,

Alex

On 7/9/25 17:12, Alexandre Ghiti wrote:
> Hi Arnd,
>
> Gentle ping as we would like to merge this in the riscv tree but we 
> need your ack (or nack).
>
> Thanks,
>
> Alex
>
> On 5/16/25 16:37, Alexandre Ghiti wrote:
>> Hi Arnd,
>>
>> Do you think we can merge that for 6.16? It is nice improvement for us.
>>
>> Thanks,
>>
>> Alex
>>
>> On 26/04/2025 16:56, Ignacio Encinas wrote:
>>> Motivated by [1]. A couple of things to note:
>>>
>>> RISC-V needs a default implementation to fall back on. There is one
>>> available in include/uapi/linux/swab.h but that header can't be 
>>> included
>>> from arch/riscv/include/asm/swab.h. Therefore, the first patch in this
>>> series moves the default implementation into asm-generic.
>>>
>>> Tested with crc_kunit as pointed out here [2]. I can't provide
>>> performance numbers as I don't have RISC-V hardware yet.
>>>
>>> [1] 
>>> https://lore.kernel.org/all/20250302220426.GC2079@quark.localdomain/
>>> [2] 
>>> https://lore.kernel.org/all/20250216225530.306980-1-ebiggers@kernel.org/ 
>>>
>>>
>>> Signed-off-by: Ignacio Encinas <ignacio at iencinas.com>
>>> ---
>>> Changes in v4:
>>>
>>> - Add missing include in the 1st patch, reported by
>>> https://lore.kernel.org/all/202504042300.it9RcOSt-lkp@intel.com/
>>> - Rewrite the ARCH_SWAB macro as suggested by Arnd
>>> - Define __arch_swab64 for CONFIG_32BIT (Ben)
>>> - Link to v3: 
>>> https://lore.kernel.org/r/20250403-riscv-swab-v3-0-3bf705d80e33@iencinas.com
>>>
>>> Arnd, I know you don't like Patch 1 but I tried your suggestions and
>>> couldn't make them work. Please let me know if I missed anything [3] 
>>> [4]
>>>
>>> [3] 
>>> https://lore.kernel.org/linux-riscv/f5464e26-faa0-48f1-8585-9ce52c8c9f5f@iencinas.com/
>>> [4] 
>>> https://lore.kernel.org/linux-riscv/b3b59747-0484-4042-bdc4-c067688e3bfe@iencinas.com/
>>>
>>> Changes in v3:
>>>
>>> PATCH 2:
>>>    Use if(riscv_has_extension_likely) instead of asm goto (Eric). It
>>>    looks like both versions generate the same assembly. Perhaps we 
>>> should
>>>    do the same change in other places such as 
>>> arch/riscv/include/asm/bitops.h
>>> - Link to v2: 
>>> https://lore.kernel.org/r/20250319-riscv-swab-v2-0-d53b6d6ab915@iencinas.com
>>>
>>> Changes in v2:
>>> - Introduce first patch factoring out the default implementation into
>>>    asm-generic
>>> - Remove blank line to make checkpatch happy
>>> - Link to v1: 
>>> https://lore.kernel.org/r/20250310-riscv-swab-v1-1-34652ef1ee96@iencinas.com
>>>
>>> ---
>>> Ignacio Encinas (2):
>>>        include/uapi/linux/swab.h: move default implementation for 
>>> swab macros into asm-generic
>>>        riscv: introduce asm/swab.h
>>>
>>>   arch/riscv/include/asm/swab.h   | 62 
>>> +++++++++++++++++++++++++++++++++++++++++
>>>   include/uapi/asm-generic/swab.h | 33 ++++++++++++++++++++++
>>>   include/uapi/linux/swab.h       | 33 +---------------------
>>>   3 files changed, 96 insertions(+), 32 deletions(-)
>>> ---
>>> base-commit: a7f2e10ecd8f18b83951b0bab47ddaf48f93bf47
>>> change-id: 20250307-riscv-swab-b81b94a9ac1b
>>>
>>> Best regards,
>
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