Re: Bug#111581: [bcollins@debian.org: Bug#111581: what to do about umul instructions and old SPARC boxen]

[ilmari@ping.uio.no (Dagfinn Ilmari Mannsåker)]

Philip Blundell <pb@nexus.co.uk> writes:

>>cpu             : Cypress/ROSS CY7C601
>
> I think that is indeed a SPARCv7 chip.  Looks like the "sun4m implies
> sparcv8" rule is not entirely hard and fast.

One thing to check: if you have openpromfs mounted you could see what
/proc/openprom/<CPU-name@addr>/sparc-version says. It should tell what
SPARC version the CPU really implements (or claims to implement).

I apologize if this has already been checked, but I couldn't see any
evidence of it neither in the BTS nor the list archive.

> Globally enabling kernel emulation of umul for sun4m shouldn't do any
> harm, so that seems like the best approach.  Or, if one wanted to be
> really careful, the kernel does know the exact cpu model so the
> emulation could be enabled only for those Cypress parts.

If compiled-in the kernel could possibly check the above entry in
OpenProm to decide and fall back to something safe if it's not.

-- 
ilmari