Messages in this thread Patch in this message | | | From | Toshi Kani <> | Subject | [PATCH] x86, pat: Add comments to cachemode translation tables | Date | Wed, 22 Jul 2015 12:06:11 -0600 |
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Add comments to the cachemode translation tables to clarify that the default values are set as minimal supported mode, which are necessary to handle WC and WT fallback to UC- when they are not enabled.
Signed-off-by: Toshi Kani <toshi.kani@hp.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Borislav Petkov <bp@suse.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> --- Ingo, please replace the patch below with this patch. https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg937806.html --- arch/x86/mm/init.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 8533b46..1d8a83d 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -30,8 +30,11 @@ /* * Tables translating between page_cache_type_t and pte encoding. * - * Minimal supported modes are defined statically, they are modified - * during bootup if more supported cache modes are available. + * The default values are defined statically as minimal supported mode; + * WC and WT fall back to UC-. pat_init() updates these values to support + * more cache modes, WC and WT, when it is safe to do so. See pat_init() + * for the details. Note, __early_ioremap() used during early boot-time + * takes pgprot_t (pte encoding) and does not use these tables. * * Index into __cachemode2pte_tbl[] is the cachemode. *
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