Re: [PATCH 2/3] sparc32: emulate casa on V8 CPUs

[Ramin Moussavi]

Hi Imre,

On Thu, 15 Oct 2026, Imre Kaloz wrote:
> A library that wants to keep its fallback can probe casa once under a
> SIGILL handler, and that works on every kernel without new ABI.
> Whichever way you go, use ASI 0x0A: it also runs natively on LEON
> parts that have casa.

thanks, I agree. For uClibc-ng I will go with the probe at startup,
with ASI 0x0A -- good point, the existing code uses 0x80.

The kernel version is no help here because of backports, so the probe
is the only way that works today. An AT_HWCAP bit would still be nicer
for code that cannot install a signal handler at startup, libgcc for
example. If Andreas wants one: on sparc64 init_sparc64_elf_hwcap()
sets bits by the index in hwcaps[], so the next entry there would take
bit 28, the bit Magnus' RFC used. A NULL placeholder at that index,
as for crypto, would keep it reserved.

Thanks,
Ramin