lkml.org 
[lkml]   [2003]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Virtual alias cache coherency results (was: x86, ARM, PARISC, PPC, MIPS and Sparc folks please run this)
Hi Jamie,

Thanks for posting the summary of your experiment - very useful!

* Jamie Lokier <jamie@shareable.org> [2003-09-10]:
>
> Validity of SHMLBA value
> ........................
>
> Many CPUs offer virtual cache coherency when the aliases are separated
> by a certain CPU-dependent multiple. In principle, all
> Linux-supported architectures _should_ have a multiple which makes
> virtual aliases coherent, because it's defined in the API as "SHMLBA".
> However, on some specific CPUs, no coherent multiple was found.
>
> Valid kernel SHMLBA: Sparc, PA-RISC, MIPS
> (plus all the coherent architectures)
> SHMLBA not valid: ARM, m68k
> SHMLBA not defined: SH

What's the basis for deciding wheter SHMLBA is defined or not? There are
definitions of SHMLBA in include/asm-sh/shmparam.h and
include/asm-sh64/shmparam.h for the kernel. The sh64 /usr/include/asm
headers have effectively the same thing (not identical because the copy
I'm looking at hasn't been synced with the latest kernel sources), and I
assume the sh userland is OK too (haven't checked though).

In both cases the kernel headers are showing correct and useful values :
16k for SH-4 in the sh file (16k direct-mapped, or 32k 2-way associative
on latest devices), 8k for SH-5 in the sh64 file (32k 4-way
associative).

Cheers
Richard

--
Richard \\\ SuperH Core+Debug Architect /// .. At home ..
P. /// richard.curnow@superh.com /// rc@rc0.org.uk
Curnow \\\ http://www.superh.com/ /// www.rc0.org.uk
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:48    [W:0.082 / U:0.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site