Re: [PATCH] cpuid.4: note which CPUs don't support CPUID and what happens

[Alejandro Colomar <alx@kernel.org>]

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Hi,

On Thu, Jan 04, 2024 at 11:31:21PM +0100, наб wrote:
> "Early 486" comes from an uncited wikipedia table, added in
>   https://en.wikipedia.org/w/index.php?title=CPUID&diff=prev&oldid=592047209
>   https://en.wikipedia.org/w/index.php?title=CPUID&diff=prev&oldid=592047978
> but I spot-checked the rest of the table accurate to CPUs in my house
> (the oldest of which is an original Celeron, so no 486),
> and "early 486" is better than "early x86" which can mean anything.
> 
> This does leave earlier x86 unmentioned,
> but Linux hasn't targeted those in over a decade,
> so they're out of scope anyway.
> 
> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>

Patch applied.  Thanks!

Have a lovely day,
Alex

> ---
>  man4/cpuid.4 | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/man4/cpuid.4 b/man4/cpuid.4
> index bd883e6d3..0b38fabe3 100644
> --- a/man4/cpuid.4
> +++ b/man4/cpuid.4
> @@ -69,7 +69,9 @@ .SH NOTES
>  There is no support for CPUID functions that require additional
>  input registers.
>  .P
> -Very old x86 CPUs don't support CPUID.
> +Early i486 CPUs do not support the CPUID instruction;
> +.\" arch/x86/kernel/cpuid.c cpuid_open()
> +opening this device for those CPUs fails with EIO.
>  .SH SEE ALSO
>  .BR cpuid (1)
>  .P
> -- 
> 2.39.2



-- 
<https://www.alejandro-colomar.es/>
Looking for a remote C programming job at the moment.

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