Messages in this thread |  | | Date | Tue, 23 Jan 2001 19:12:36 +0100 (MET) | From | Roman Zippel <> | Subject | Re: ioremap_nocache problem? |
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Hi,
On Tue, 23 Jan 2001, Mark Mokryn wrote:
> ioremap_nocache does the following: > return __ioremap(offset, size, _PAGE_PCD); > > However, in drivers/char/mem.c (2.4.0), we see the following: > > /* On PPro and successors, PCD alone doesn't always mean > uncached because of interactions with the MTRRs. PCD | PWT > means definitely uncached. */ > if (boot_cpu_data.x86 > 3) > prot |= _PAGE_PCD | _PAGE_PWT; > > Does this mean ioremap_nocache() may not do the job?
ioremap creates a new mapping that shouldn't interfere with MTRR, whereas you can map a MTRR mapped area into userspace. But I'm not sure if it's correct that no flag is set for boot_cpu_data.x86 <= 3...
bye, Roman
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