Re: Cache incoherencies
Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 27 Aug 1999 15:08:13 +0100 (BST)
> To access a piece of memory with a uncached-pte you can use a
> kmap_uncached() that maybe a variant of a plain kmap(). kmap() will avoid
> you to waste lots virtual address space by using the per-CPU virtual
> addresses allocated in the fixmap area. You'll have only to run an invlpg
> before accessing the data (after updating the pte). See the bigmem patch
> for more details.
Thats an x86ism. Per page cacheability is an unusual but handy feature. Also
what CPU's do with two maps of the same page one cached and one uncached is
fairly variable and rarely what you want, making remapping games require some
arch specific care
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