> Date: Sun, 21 Jul 2024 19:52:28 +0200
> From: Jeremie Courreges-Anglas <jca@wxcvbn.org>
> 
> On Fri, Jul 19, 2024 at 04:39:04PM +0200, Mark Kettenis wrote:
> > > Date: Wed, 17 Jul 2024 16:58:50 +0200
> > > From: Mark Kettenis <mark.kettenis@xs4all.nl>
> > > 
> > > > Date: Tue, 16 Jul 2024 22:10:26 +0200
> > > > From: Christian Weisgerber <naddy@mips.inka.de>
> > > > 
> > > > The patch below populates arm64 hwcaps from the ID_AA64ISAR0 register.
> > > > 
> > > > I didn't look at other registers and I don't know if we want to do
> > > > it this way.  There is the question of keeping this in sync with
> > > > the CPU_ID_AA64* sysctl() for filtering out unsupported options.
> > > > 
> > > > It's intended as a provisional change to signal the common AES,
> > > > SHA, CRC32 instruction extensions via elf_aux_info(), so people can
> > > > check how that interacts with ports.
> > > 
> > > Sorry, but I discussed with jca@ that we (I) would tackle this after
> > > my diff goes in that adds emulation of the ID registers as that
> > > reorganizes how thie cpi_id_aa64xxx registers are sanitized.
> > > 
> > > We want to set the hwcap flags at that point instead of in
> > > cpu_identify().
> > 
> > So here is a diff.  That provides that populates hwcap and hwcap2 in a
> > way that is consistent with what the sysctls and emulated ID
> > instructions provide.
> > 
> > Note that this assumes the patch that enables emulated ID instructions
> > has gone in.  Until that happens, either drop trhe setting of
> > HWCAP_CPUID or apply that patch first (and make sure you don't boot
> > into a snapshot kernel).
> > 
> > I'd like to move forward with both patches such that we can catch any
> > fallout early.
> > 
> > ok?
> 
> Matches what https://docs.kernel.org/arch/arm64/elf_hwcaps.html says.
> ok jca@
> 
> I'll be looking at the cpuid bits next.

Thanks!

I've commited the hwcap/hwcap2 stuff without setting HWCAP_CPUID for
now.  Hopefully I can commit the emulation bits soon and add
HWCAP_CPUID.

Patrick, can you take a look a that diff?