Re: [Qemu-devel] problem using AHCI on xen fvm

[Zhang, Eniac]

Hi Stefano,

You are a genius.   Qemu2.0.0 works fine with my AHCI hack.  

Then I took a look at the patch.  That fix is exactly what's missing in qemu 
1.6.1.  I ported back that one fix and all is working now.  I am running full 
test now to make sure that's the right thing to do.  

Thanks for the help/Eniac


> # test with vanilla-xen
> 
> Qemu-1.6.1-vanilla with 440fx chipset: no corruption
> 
> Qemu-1.6.1 with AHCI patch and 440fx chipset: corruption

Can you try with a more recent QEMU version? Maybe QEMU 2.0?


> So the problem lies between the interaction between AHCI controller 
> and xen.  Has anyone else tried this and/or can take a look to see what’s 
> happening here?

In these cases it is usually a mapcache (see xen-mapcache.c) problem.
Not a bug in the mapcache per se, but maybe it is not called correctly from 
common code. To give you an idea of a possible bad interaction between the 
mapcache and common code, see:

commit a41087bc7110e8378cd49ddd06aa7c9d361f3673
Author: Stefano Stabellini <address@hidden>
Date:   Thu Jan 30 12:46:05 2014 +0000

    address_space_translate: do not cross page boundaries