Messages in this thread | | | From | Linus Torvalds <> | Date | Wed, 21 Mar 2018 18:26:38 -0700 | Subject | Re: [RFC PATCH 2/3] x86/io: implement 256-bit IO read and write |
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On Tue, Mar 20, 2018 at 7:42 AM, Alexander Duyck <alexander.duyck@gmail.com> wrote: > > Instead of framing this as an enhanced version of the read/write ops > why not look at replacing or extending something like the > memcpy_fromio or memcpy_toio operations?
Yes, doing something like "memcpy_fromio_avx()" is much more palatable, in that it works like the crypto functions do - if you do big chunks, the "kernel_fpu_begin/end()" isn't nearly the issue it can be otherwise.
Note that we definitely have seen hardware that *depends* on the regular memcpy_fromio()" not doing big reads. I don't know how hardware people screw it up, but it's clearly possible.
So it really needs to be an explicitly named function that basically a driver can use to say "my hardware really likes big aligned accesses" and explicitly ask for some AVX version if possible.
Linus
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