Messages in this thread | | | Date | Sun, 04 Feb 2007 17:49:58 +0100 | From | Pierre Ossman <> | Subject | Re: [RFC] [PATCH] Fix up needless kmap:s |
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Alex Dubov wrote: > The patch looks ok. > > However, due to certain peculiarities with memorystick and xd I have to emulate a scatter-gather > in software. Considering that this particular aspect of implementation is the same for all card > types on this TI chip, it can be shared by tifm_sd driver as well. In this case highmem won't be > needed to be avoided and kmap_atomic will come back (may be). > >
Fair enough. Just make sure you handle the big problem case (kmap only maps a single page, not the entire sg entry).
> And, by the way, to what extent pagefault_enable/pagefault_disable calls are needed? They are > present in k(u)map_atomic even for non-highmem pages/architectures. > >
They tell the page fault handler that it may not sleep on a page fault. Currently it only has the behaviour of disabling preemption though. I'd guess it is present for non-highmem so that things behave somewhat similar for both the highmem and non-highmem cases.
Rgds
-- -- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org PulseAudio, core developer http://pulseaudio.org rdesktop, core developer http://www.rdesktop.org
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