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

[Santosh Jodh <Santosh.Jodh@xxxxxxxxxx>]

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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