Messages in this thread | | | Date | Tue, 8 Dec 2009 22:30:05 +0800 | From | Jie Zhang <> | Subject | Re: [PATCH] NOMMU: use copy_*_user_page() in access_process_vm() |
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On 12/08/2009 10:19 PM, David Howells wrote: > Jie Zhang<jie.zhang@analog.com> wrote: > >> I agree on using 0 instead of NULL. But for !MMU, I think, vaddr is always as >> same as addr. So we don't need to pass it? > > FRV flushes the vaddr because in MMU mode the cache flush instructions take > virtual addresses, so if we pass addr as vaddr, I can use the same cache flush > code for both modes. I suspect it makes little difference to the amount of > code if we pass that rather than 0, as the value is already computed, and > either way, it's going to take one instruction to set up the argument. > > Note that Blackfin assumes that it may use the dst address for flushing - an > assumption that isn't valid in MMU mode with a VIVT cache (which I presume > Blackfin isn't, but other CPUs are). > Thanks for your explanation. Now I understand why passing add as vaddr is better.
Jie
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