Re: [PATCH net-next v6 07/23] zinc: ChaCha20 ARM and ARM64 implementations

Hi Ard,

On Sat, Sep 29, 2018 at 8:16 AM Ard Biesheuvel
[off-list ref] wrote:

quoted

You mean to say that since these nobs are def_bool y and are
essentially "depends on ARM", then I should just straight up use
CONFIG_ARM? I had thought about this, but figured this would make it
easier to later make these optional or have other options block them
need be, or even if the dependencies and requirements for having them
changes (for example, with UML on x86). I think doing it this way
gives us some flexibility later on. So if that's a compelling enough
reason, I'd like to keep those.

Sure. But probably better to be consistent then, and stop using
CONFIG_ARM directly in your code.

Ack.

quoted

The reason it was added was indeed because of:
https://lists.01.org/pipermail/kbuild-all/2018-September/053114.html
-- exactly what you suspected, ARCH_RPC. Have a better suggestion than
!CPU_32v3?

Yes, you could just add

asflags-$(CONFIG_CPU_32v3) += -march=armv4

with a comment stating that we don't actually support ARMv3 but only
use it as a code generation target for reasons unrelated to the ISA

Alright, I'll do exactly that. Though, if the rationale for this has
to do only with codegen -- with what the C compiler does -- then
shouldn't this be set globally for CONFIG_CPU_32v3? I couldn't find
any macros that test against __LINUX_ARM_ARCH__ being 3 in the
assembly, so this shouldn't be a problem I don't think. Maybe I'll
send a patch.

Jason