Re: [PATCH] mm: Avoid overlap the fixmap area on i386

Thomas Gleixner
2014-10-28T17:29:19Z

On Tue, 28 Oct 2014, H. Peter Anvin wrote:
> On 10/28/2014 04:06 AM, Thomas Gleixner wrote:
> >>
> >> The available address we can use is lower than FIXADDR_BOOT_START. So
> >> We will set the kmap boundary below the FIXADDR_BOOT_START, if configure
> >> the high memory.
> >>
> >> If we configure the high memory, the vmalloc reserve area should end
> >> up to PKMAP_BASE, otherwise should end up to FIXADDR_BOOT_START.
> >
> > Which is not really a problem, because the FIXADDR_BOOT area is only
> > used during boot for early_ioremap() and it's unused when ioremap() is
> > functional. vmalloc becomes available after early boot so the
> > FIXADDR_BOOT area is available for reuse.
> >
>
> Given the very limited address space available on i386, it would be
> extremely undesirable to not reuse address space when possible.

Fair enough. Then we should do that for the highmem=y case as well.

Thanks,

tglx