Messages in this thread | | | Date | Tue, 5 Dec 2006 16:57:12 -0800 | From | "Matt Reimer" <> | Subject | Re: [PATCH] mm: D-cache aliasing issue in cow_user_page |
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On 12/5/06, David Miller <davem@davemloft.net> wrote: > From: "Matt Reimer" <mattjreimer@gmail.com> > Date: Mon, 4 Dec 2006 23:38:13 -0800 > > > In light of James Bottomsley's commit[1] declaring that kmap() and > > friends now have to take care of coherency issues, is the patch "mm: > > D-cache aliasing issue in cow_user_page"[2] correct, or could it > > potentially cause a slowdown by calling flush_dcache_page() a second > > time (i.e. once in an architecture-specific kmap() implementation, and > > once in cow_user_page())? > > kmap() is a NOP unless HIGHMEM is configured. > > Therefore, it cannot possibly take care of D-cache aliasing issues > across the board.
Right, but isn't he declaring that each architecture needs to take care of this? So, say, on ARM we'd need to make kunmap() not a NOP and call flush_dcache_page() ?
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