Re: [Xen-devel] [PATCH] xen/x86: Zero out .bss for PV guests

[Boris Ostrovsky]

On 02/24/2016 09:15 AM, Andrew Cooper wrote:
> On 24/02/16 14:12, David Vrabel wrote:
> > On 22/02/16 22:06, Boris Ostrovsky wrote:
> > > Baremetal kernels clear .bss early in the boot. Since Xen PV guests don't
> > > excecute that early code they should do it too.
> > >
> > > (Since we introduce macros for specifying 32- and 64-bit registers we
> > > can get rid of ifdefs in startup_xen())
> > .bss must have been cleared for PV guests otherwise they would be
> > horribly broken.  What was the method and why is it no longer sufficient?

I couldn't find this being done anywhere, hence this patch.

> The domain builder hands out zeroed pages.  I don't believe we guarantee
> that the guests RAM is clean, but it is in practice.

OK, that's what I suspected but didn't actually look.

I, in fact, wonder whether this should go to stable trees as well.

-boris