Re: [PATCH] Add VDSO time function support for x86 32-bit kernel

[H. Peter Anvin]

On 12/13/2012 11:32 AM, Andy Lutomirski wrote:
> x32's vdso cheats -- x32 code can see high addresses just fine.  The
> toolchain just makes it difficult.
>
> Your best bet is probably to just map the vvar page twice -- once at
> the same address as native 32-bit mode (but only for compat tasks)
> would use and once in the usual fixmap location.  You can't use the
> fixmap for the compat mapping, though, since it would be a *user*
> address.
>
> For HPET support, you'd have to have special support.  I'd say to skip
> it for compat mode.

Whatever data you need you can just map it into the vdso range.  There 
really shouldn't be anything special about that at all.

The fixmap stuff is an x86-64 legacy that you don't have to worry about, 
obviously.

	-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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