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Date: Wed, 24 Feb 2016 14:58:40 +0000 From: David Vrabel <david.vrabel@...rix.com> To: Boris Ostrovsky <boris.ostrovsky@...cle.com>, Andrew Cooper <andrew.cooper3@...rix.com>, <konrad.wilk@...cle.com> CC: <xen-devel@...ts.xenproject.org>, <mcgrof@...nel.org>, <linux-kernel@...r.kernel.org> Subject: Re: [Xen-devel] [PATCH] xen/x86: Zero out .bss for PV guests On 24/02/16 14:52, Boris Ostrovsky wrote: > 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. Yes. Can you respin with a commit message explaining? (Or just provide the message here and I'll fix it up). David
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