Re: [Qemu-devel] [RFC][PATCH 10/15] memory: Rework sub-page handling

[Peter Maydell]

On 6 May 2013 15:26, Jan Kiszka <address@hidden> wrote:
> Simplify the sub-page handling by implementing it directly in the
> dispatcher instead of using a redirection memory region. We extend the
> phys_sections entries to optionally hold a pointer to the sub-section
> table that used to reside in the subpage_t structure. IOW, we add one
> optional dispatch level below the existing radix tree.
>
> address_space_lookup_region is extended to take this additional level
> into account. This direct dispatching to that target memory region will
> also be helpful when we want to add per-region locking control.

This patch seems to break vexpress-a9. Test case if you want it:
http://staging.people.linaro.org/~peter.maydell/vexpress-3.8.tar.gz
(125MB) Edit the 'runme' script to fix up the paths to kernel/initrd/dtb
and then run it; before this patch it boots, afterwards it doesn't
even manage to start the kernel.

My guess is you've broken subregion-sized mmio regions somehow
(and/or regions which are larger than a page in size but start
or finish at a non-page-aligned address), and probably in particular
the arm_gic regions that a9mpcore maps...

thanks
-- PMM