Re: [Qemu-devel] TARGET_PAGE_SIZE > host page size

[Edgar E. Iglesias]

On Fri, Sep 21, 2007 at 04:43:37PM +0100, Paul Brook wrote:
> On Friday 21 September 2007, Edgar E. Iglesias wrote:
> > Hello,
> >
> > I'm working on a new target port and the linux-user emulation is fairly
> > functional and passing quite extensive test-suites.
> >
> > I've got a problem though, my target has 8K page sizes, so for example when
> > running on a x86 host TARGET_PAGE_SIZE > host page size.
> >
> > I'm not very familiar with linux-user/mmap.c, but I though I'd let you know
> > that with this patch things seem to be working fine for me. I am not sure
> > if the patch is correct so if anyone with more experience sees an obvious
> > flaw I'd appreciate to know.
> 
> qemu_host_page_size is always >= TARGET_PAGE_SIZE. See exec.c.
> There are several existing target that have >4k page sizes.

Thanks alot for the info I'll investigate this more.

A quick look shows that qemu_real_host_page_size is not = TARGET_PAGE_SIZE. As 
far as I can see, target_mmap is not doing the right thing when the guest page 
size is larger than the host page size. mmap might return an unaligned area to 
the guest code which results in target_mmap returning -1. Maybe I forgot to 
define something in the target specific files?

Best regards
-- 
Edgar E. Iglesias
Axis Communications AB