Re: [Xen-devel] Using debug-key 'o: Dump IOMMU p2m table, locks up machine

[Santosh Jodh <Santosh.Jodh@xxxxxxxxxx>]

BTW, I should add that 1:1 mapping for the VM seems very suspicious. Wei can 
comment for sure.

> -----Original Message-----
> From: Santosh Jodh
> Sent: Friday, August 31, 2012 4:58 PM
> To: 'Sander Eikelenboom'
> Cc: wei.wang2@xxxxxxx; xen-devel@xxxxxxxxxxxxx
> Subject: RE: Using debug-key 'o: Dump IOMMU p2m table, locks up machine
> 
> 1:1 mapping is not the common case for gfn-mfn. It is hard to say how much
> output would shrink by dumping contiguous ranges instead of individual pfns
> in the general case.
> 
> > -----Original Message-----
> > From: Sander Eikelenboom [mailto:linux@xxxxxxxxxxxxxx]
> > Sent: Friday, August 31, 2012 4:16 PM
> > To: Santosh Jodh
> > Cc: wei.wang2@xxxxxxx; xen-devel@xxxxxxxxxxxxx
> > Subject: Re: Using debug-key 'o: Dump IOMMU p2m table, locks up
> > machine
> >
> >
> > Saturday, September 1, 2012, 12:57:45 AM, you wrote:
> >
> > > The dump should complete - would be curious to see how long it takes
> > > on
> > serial console. What baudrate is the console running at?
> >
> > I think for ages, this part seems only to cover a bit of the first of
> > 3 pv guests which have devices passed through.
> > 38400
> >
> > And i wonder if the information is very valuable, gfn == mfn for every line
> ...
> > at an increment of 1 ...
> > Perhaps a uhmmm more compact way of getting the interesting data
> would
> > be handy ?
> > Or is this the intended output ?
> >
> > > The code does allow processing of pending softirqs quite frequently.
> > > I am
> > not sure why you are still seeing SATA errors.
> >
> > The machine is completely unresponsive in every way.
> >
> > And using it with "xl debug-keys o" is never going to work i guess,
> > since the information flood is far larger than "xl dmesg" keeps ?
> >
> >
> >
> > >> -----Original Message-----
> > >> From: Sander Eikelenboom [mailto:linux@xxxxxxxxxxxxxx]
> > >> Sent: Friday, August 31, 2012 3:43 PM
> > >> To: Santosh Jodh
> > >> Cc: wei.wang2@xxxxxxx; xen-devel@xxxxxxxxxxxxx
> > >> Subject: Re: Using debug-key 'o: Dump IOMMU p2m table, locks up
> > >> machine
> > >>
> > >>
> > >> Saturday, September 1, 2012, 12:24:32 AM, you wrote:
> > >>
> > >> > Depending on how many VMs you have and the size of the IOMMU
> > p2m
> > >> table, it can take a while. It should not be infinite though.
> > >>
> > >> > How many VMs do you have running?
> > >>
> > >> 15
> > >>
> > >> > Can you please send the serial output when you press 'o'?
> > >>
> > >> Attached, to the end you will see the s-ata errors coming through
> > >> while the dump still runs.
> > >> This is not a complete dump, only a few minutes after which i did a
> > >> hard reset.
> > >>
> > >> > Santosh
> > >>
> > >> >> -----Original Message-----
> > >> >> From: Sander Eikelenboom [mailto:linux@xxxxxxxxxxxxxx]
> > >> >> Sent: Friday, August 31, 2012 2:45 PM
> > >> >> To: Santosh Jodh; wei.wang2@xxxxxxx
> > >> >> Cc: xen-devel@xxxxxxxxxxxxx
> > >> >> Subject: Using debug-key 'o: Dump IOMMU p2m table, locks up
> > >> >> machine
> > >> >>
> > >> >>
> > >> >> I was trying to use the 'o' debug key to make a bug report about
> > >> >> an "AMD-
> > >> Vi:
> > >> >> IO_PAGE_FAULT".
> > >> >>
> > >> >> The result:
> > >> >> - When using "xl debug-keys o", the machine seems in a infinite
> > >> >> loop, can hardly login, eventually resulting in a kernel RCU
> > >> >> stall and complete
> > >> lockup.
> > >> >> - When using serial console: I get a infinite stream of "gfn:  mfn: "
> > >> >> lines, mean while on the normal console, S-ATA devices are
> > >> >> starting to
> > >> give errors.
> > >> >>
> > >> >> So either option trashes the machine, other debug-keys work fine.
> > >> >>
> > >> >> Machine has a 890-fx chipset and AMD phenom x6 proc.
> > >> >>
> > >> >> xl dmesg with bootup and output from some other debug-keys is
> > >> attached.
> > >> >>
> > >> >> --
> > >> >>
> > >> >> Sander
> > >>
> > >>
> > >>
> > >>
> > >> --
> > >> Best regards,
> > >>  Sander                            mailto:linux@xxxxxxxxxxxxxx
> >
> >
> >
> >
> > --
> > Best regards,
> >  Sander                            mailto:linux@xxxxxxxxxxxxxx


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