Re: [Qemu-devel] [PATCH] linux-user: Align mmap memory to the target page size.

[Richard Henderson <rth@twiddle.net>]

On 01/14/2010 04:38 PM, Richard Henderson wrote:
> Previously, mmap_find_vma could return addresses not properly aligned
> to the target page size.  This of course led to all sorts of odd
> problems down the road.
>
> The trivial fix, to simply reject the unaligned address and continue
> searching the address space by increments of one page, is not a good
> idea when there's a 64-bit address space involved.  The kernel may well
> continue to return the last available address which we've already
> rejected while we search upward from e.g. 2**42 from 2**64.
>
> This patch uses a more complex search algorithm that takes the result
> of the previous allocation into account.  We normally search upward,
> but notice 2 consecutive results and start searching downward instead.

I've failed to take guest_base into account properly; my testing 
happened to have guest_base = 0.  New patch to follow.


r~