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[POWERPC] Fix cache line vs. block size confusion

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We had an historical confusion in the kernel between cache line
and cache block size. The former is an implementation detail of
the L1 cache which can be useful for performance optimisations,
the later is the actual size on which the cache control
instructions operate, which can be different.

For some reason, we had a weird hack reading the right property
on powermac and the wrong one on any other 64 bits (32 bits is
unaffected as it only uses the cputable for cache block size
infos at this stage).

This fixes the booting-without-of.txt documentation to mention
the right properties, and fixes the 64 bits initialization code
to look for the block size first, with a fallback to the line
size if the property is missing.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Benjamin Herrenschmidt
2007-10-28 08:49:28 +11:00
committed by Paul Mackerras
parent fb293ae1c0
commit 20474abda6
2 changed files with 19 additions and 14 deletions
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19
arch/powerpc/kernel/setup_64.c
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@@ -291,23 +291,16 @@ static void __init initialize_cache_info(void)
if ( num_cpus == 1 ) {
const u32 *sizep, *lsizep;
u32 size, lsize;
const char *dc, *ic;
/* Then read cache informations */
if (machine_is(powermac)) {
dc = "d-cache-block-size";
ic = "i-cache-block-size";
} else {
dc = "d-cache-line-size";
ic = "i-cache-line-size";
}
size = 0;
lsize = cur_cpu_spec->dcache_bsize;
sizep = of_get_property(np, "d-cache-size", NULL);
if (sizep != NULL)
size = *sizep;
lsizep = of_get_property(np, dc, NULL);
lsizep = of_get_property(np, "d-cache-block-size", NULL);
/* fallback if block size missing */
if (lsizep == NULL)
lsizep = of_get_property(np, "d-cache-line-size", NULL);
if (lsizep != NULL)
lsize = *lsizep;
if (sizep == 0 || lsizep == 0)
@@ -324,7 +317,9 @@ static void __init initialize_cache_info(void)
sizep = of_get_property(np, "i-cache-size", NULL);
if (sizep != NULL)
size = *sizep;
lsizep = of_get_property(np, ic, NULL);
lsizep = of_get_property(np, "i-cache-block-size", NULL);
if (lsizep == NULL)
lsizep = of_get_property(np, "i-cache-line-size", NULL);
if (lsizep != NULL)
lsize = *lsizep;
if (sizep == 0 || lsizep == 0)