Re: [Xen-devel] PV guest with PCI passthrough crash on Xen 4.8.3 inside KVM when booted through OVMF

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 19/02/18 17:46, Juergen Gross wrote:
> On 19/02/18 18:29, Marek Marczykowski-Górecki wrote:
>> On Mon, Feb 19, 2018 at 06:23:40PM +0100, Juergen Gross wrote:
>>> On 16/02/18 20:54, Marek Marczykowski-Górecki wrote:
>>>> Just before the BUG(), there is a call to xen_raw_console_write(). But
>>>> apparently it was too early...
>>> Depends.
>>>
>>> With a debug enabled hypervisor and appropriate log levels set
>>> (guest_loglvl=all) you should see the message in the hypervisor log.
>> I've tried with guest_loglvl=all, but there was nothing. Wouldn't it
>> make sense to enable this functionality also in non-debug builds - only
>> guarded by guest_loglvl=all option?
> Hmm, I think this is on purpose to avoid the possibility of a guest
> flooding the hypervisor log.
>
> Maybe adding a new option (e.g. guest_messages=on/off) switchable at
> runtime only via "xl set-parameters" would avoid the general flooding
> problem while enabling diagnosis of such problems?

You want to recompile with CONFIG_VERBOSE, which you need EXPERT mode to
introduce into a release build.

~Andrew

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