Re: MMIO and gcc re-ordering issue

Linus Torvalds
2008-05-27T17:32:04Z

On Tue, 27 May 2008, Linus Torvalds wrote:
>
> Here's a UNTESTED patch for x86 that may or may not compile and work, and
> which serializes (on a compiler level) the IO accesses against regular
> memory accesses.

Ok, so it at least boots on x86-32. Thus probably on x86-64 too (since the
code is now shared). I didn't look at whether it generates much bigger
code due to the potential extra serialization, but some of the code
generation I looked at looked fine.

IOW, it doesn't at least create any _obviously_ worse code, and it should
be arguably safer than assuming the compiler does volatile accesses the
way we want it to.

Linus