Messages in this thread | | | Date | Sat, 8 Dec 2007 20:44:26 +0000 | From | Ralf Baechle <> | Subject | Re: use of fixmap on non-x86/sh? |
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On Fri, Nov 30, 2007 at 04:14:55PM -0600, Kumar Gala wrote:
> Ben and I are talking about using fixmap on ppc for similar applications to > it use on x86. However in poking around other arch's (sparc, mips) they > appear to have some support but not as complete as x86. > > For example both SPARC & MIPS reference __set_fixmap() in asm/fixmap.h but > I can't find an implementation on either. > > So I was wondering if there was some reason fixmap isn't as well supported > or if its just used for a specific function on those SPARC, MIPS, etc. and > they dont need as much functionality out of it as x86 does.
MIPS uses fixmap for two purposes:
o In some cases it is possibly to avoid or optimize a cacheflush by creating a temporary mapping. The mechanism works very similar to what x86 and MIPS use for atomic kmaps. o Highmem.
Both manipulate pagetables directly or even insert entries directly into the TLB without pagetables as intermediate stage so __set_fixmap is indeed unused.
Ralf
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