Re: [Xen-devel] [PATCH] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes.

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Fri, Mar 8, 2013 at 10:17 AM, George Dunlap
<George.Dunlap@xxxxxxxxxxxxx> wrote:
>> I would just remove use_o_direct and BDRV_O_NOCACHE altogether
>
> Wait, aren't O_DIRECT and BDRV_O_NOCACHE required for safety?  That
> is, without these flags isn't it possible that the guest OS thinks
> that the data has made it onto stable storage, while in fact it's
> still in dom0's memory?  Or am I missing something?

And in any case, if it's a kernel bug it should be fixed in the kernel.

Alex, which dom0 kernel are you using? I actually seem to recall this
being a long-known bug with some versions of the pvops kernels; but I
thought it had long since been fixed.  Kondrad / IanC, can you
comment?

Alex, if that's the case and if you're using a distro kernel maybe you
should try to push for a backport?

 -George

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