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-   -   Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled) (http://www.linux-archive.org/debian-kernel/516976-bug-623594-closed-ben-hutchings-ben-decadent-org-uk-bug-623594-system-freeze-during-boot-iommmu-enabled.html)

Robin Axelsson 04-21-2011 07:05 PM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On 2011-04-21 20:03, Debian Bug Tracking System wrote:

n Thu, Apr 21, 2011 at 05:41:29PM +0200, Robin Axelsson wrote:

> Package: Debian-testing-amd64-DC-1.iso (latest version converted to boot
> USB)
> Severity: Critical
> Platform: x86_64 Linux (also .386/i686)
>
> Description of problem:

> Since I updated the firmware of my BIOS to a revision that supports AMD
> IOMMU and turned that feature on, pretty much anything that runs
> Linux fails to boot All I see about half a second after I pass the
> GRUB bootloader is a blinking cursor in the upper left corner. The
> mouse gets disabled (i.e. powered off in spite of being plugged in)
> and the keyboard doesn't even respond to caps-lock, num-lock and
> scroll-lock toggles (numlock light is constantly on).
>
> I assume that it is needless to say that this is a non-issue when

> the IOMMU feature is disabled.

[...]

So there is a bug in the BIOS, and you have a workaround for it.
I don't see a bug in Debian.

Ben.


I don't understand your statement. IOMMU is a feature that allows for
passthrough of I/O devices to virtual machines. I need this feature on
my computer but Debian doesn't work with that feature.


If this was due to a bug in the BIOS why the does it not crash Citrix
Xenserver 5.6, Windows 7 x64 or even FreeDOS/MS-DOS?


Robin.




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Ben Hutchings 04-21-2011 07:22 PM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On Thu, Apr 21, 2011 at 09:05:14PM +0200, Robin Axelsson wrote:
> On 2011-04-21 20:03, Debian Bug Tracking System wrote:
> >n Thu, Apr 21, 2011 at 05:41:29PM +0200, Robin Axelsson wrote:
> >>> Package: Debian-testing-amd64-DC-1.iso (latest version converted to boot
> >>> USB)
> >>> Severity: Critical
> >>> Platform: x86_64 Linux (also .386/i686)
> >>> > Description of problem:
> >>> Since I updated the firmware of my BIOS to a revision that supports AMD
> >>> IOMMU and turned that feature on, pretty much anything that runs
> >>> Linux fails to boot All I see about half a second after I pass the
> >>> GRUB bootloader is a blinking cursor in the upper left corner. The
> >>> mouse gets disabled (i.e. powered off in spite of being plugged in)
> >>> and the keyboard doesn't even respond to caps-lock, num-lock and
> >>> scroll-lock toggles (numlock light is constantly on).
> >>> > I assume that it is needless to say that this is a
> >>non-issue when
> >>> the IOMMU feature is disabled.
> >[...]
> >
> >So there is a bug in the BIOS, and you have a workaround for it.
> >I don't see a bug in Debian.
> >
> >Ben.
>
> I don't understand your statement. IOMMU is a feature that allows
> for passthrough of I/O devices to virtual machines. I need this
> feature on my computer but Debian doesn't work with that feature.

Like many new hardware features, IOMMUs must be correctly described
by the BIOS before an operating system can use them.

> If this was due to a bug in the BIOS why the does it not crash
> Citrix Xenserver 5.6, Windows 7 x64 or even FreeDOS/MS-DOS?

Because they don't try to use the IOMMU.

Ben.

--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
- Albert Camus



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Ben Hutchings 04-25-2011 01:48 AM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On Thu, 2011-04-21 at 22:53 +0200, Robin Axelsson wrote:
> On 2011-04-21 21:22, Ben Hutchings wrote:
> > On Thu, Apr 21, 2011 at 09:05:14PM +0200, Robin Axelsson wrote:
> >> On 2011-04-21 20:03, Debian Bug Tracking System wrote:
> >>> n Thu, Apr 21, 2011 at 05:41:29PM +0200, Robin Axelsson wrote:
> >>>>> Package: Debian-testing-amd64-DC-1.iso (latest version converted to boot
> >>>>> USB)
> >>>>> Severity: Critical
> >>>>> Platform: x86_64 Linux (also .386/i686)
> >>>>> > Description of problem:
> >>>>> Since I updated the firmware of my BIOS to a revision that supports AMD
> >>>>> IOMMU and turned that feature on, pretty much anything that runs
> >>>>> Linux fails to boot All I see about half a second after I pass the
> >>>>> GRUB bootloader is a blinking cursor in the upper left corner. The
> >>>>> mouse gets disabled (i.e. powered off in spite of being plugged in)
> >>>>> and the keyboard doesn't even respond to caps-lock, num-lock and
> >>>>> scroll-lock toggles (numlock light is constantly on).
> >>>>> > I assume that it is needless to say that this is a
> >>>> non-issue when
> >>>>> the IOMMU feature is disabled.
> >>> [...]
> >>>
> >>> So there is a bug in the BIOS, and you have a workaround for it.
> >>> I don't see a bug in Debian.
> >>>
> >>> Ben.
> >> I don't understand your statement. IOMMU is a feature that allows
> >> for passthrough of I/O devices to virtual machines. I need this
> >> feature on my computer but Debian doesn't work with that feature.
> > Like many new hardware features, IOMMUs must be correctly described
> > by the BIOS before an operating system can use them.
> >
> >> If this was due to a bug in the BIOS why the does it not crash
> >> Citrix Xenserver 5.6, Windows 7 x64 or even FreeDOS/MS-DOS?
> >
> > Because they don't try to use the IOMMU.
> >
> > Ben.
> >
>
> Ok, I have failed to activate the IOMMU feature in the XenServer (by
> adding iommu=1 after xen.gz in the /boot/extlinux.conf and running
> extlinux /boot).
[...]

I'm not sure what you mean by that. If you *do* use that option, does
XenServer boot and are you able to use PCI pass-through?

Ben.

--
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

Bastian Blank 04-25-2011 08:25 AM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On Mon, Apr 25, 2011 at 02:48:47AM +0100, Ben Hutchings wrote:
> I'm not sure what you mean by that. If you *do* use that option, does
> XenServer boot and are you able to use PCI pass-through?

PCI pass-through for pv domains does not use the IOMMU at all.

Bastian

--
... The prejudices people feel about each other disappear when they get
to know each other.
-- Kirk, "Elaan of Troyius", stardate 4372.5



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Ian Campbell 04-25-2011 09:26 AM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On Mon, 2011-04-25 at 10:25 +0200, Bastian Blank wrote:
> On Mon, Apr 25, 2011 at 02:48:47AM +0100, Ben Hutchings wrote:
> > I'm not sure what you mean by that. If you *do* use that option, does
> > XenServer boot and are you able to use PCI pass-through?
>
> PCI pass-through for pv domains does not use the IOMMU at all.

It can if you want, but it has a different Xen command line syntax to
enable it vs. enabling it for HVM guests. I can't remember what it is
right no, iommu=pv or something?

Ian.
--
Ian Campbell

Do you mean to say that I can read mail with vi too? ;-)
Didn't you know that?
:r /var/spool/mail/jk
-- Seen on #debian-mentors

Robin Axelsson 04-25-2011 10:03 AM

Bug#623594: closed by Ben Hutchings ( Bug#623594: system freeze during boot with IOMMMU enabled)
 
On 2011-04-25 03:48, Ben Hutchings wrote:

On Thu, 2011-04-21 at 22:53 +0200, Robin Axelsson wrote:

On 2011-04-21 21:22, Ben Hutchings wrote:

On Thu, Apr 21, 2011 at 09:05:14PM +0200, Robin Axelsson wrote:

On 2011-04-21 20:03, Debian Bug Tracking System wrote:

n Thu, Apr 21, 2011 at 05:41:29PM +0200, Robin Axelsson wrote:

Package: Debian-testing-amd64-DC-1.iso (latest version converted to boot
USB)
Severity: Critical
Platform: x86_64 Linux (also .386/i686)
> Description of problem:
Since I updated the firmware of my BIOS to a revision that supports AMD
IOMMU and turned that feature on, pretty much anything that runs
Linux fails to boot All I see about half a second after I pass the
GRUB bootloader is a blinking cursor in the upper left corner. The
mouse gets disabled (i.e. powered off in spite of being plugged in)
and the keyboard doesn't even respond to caps-lock, num-lock and
scroll-lock toggles (numlock light is constantly on).
> I assume that it is needless to say that this is a

non-issue when

the IOMMU feature is disabled.

[...]

So there is a bug in the BIOS, and you have a workaround for it.
I don't see a bug in Debian.

Ben.

I don't understand your statement. IOMMU is a feature that allows
for passthrough of I/O devices to virtual machines. I need this
feature on my computer but Debian doesn't work with that feature.

Like many new hardware features, IOMMUs must be correctly described
by the BIOS before an operating system can use them.


If this was due to a bug in the BIOS why the does it not crash
Citrix Xenserver 5.6, Windows 7 x64 or even FreeDOS/MS-DOS?

Because they don't try to use the IOMMU.

Ben.


Ok, I have failed to activate the IOMMU feature in the XenServer (by
adding iommu=1 after xen.gz in the /boot/extlinux.conf and running
extlinux /boot).

[...]

I'm not sure what you mean by that. If you *do* use that option, does
XenServer boot and are you able to use PCI pass-through?

Ben.



I was very surprised to find out that XenServer booted at all since it
is linux based and everything else with linux on it had failed so far.
Moreover, since XenServer is with the horse's mouth of Xen I assumed
that it is the most technologically advanced Xen implementation. So to
me it was implied that it would use IOMMU by default whenever such
feature would be available in the hardware.


When I read the documentation more thoroughly I found that the version
of Xen is merely 3.4.2 and not the latest 4.1. I also found it that it
runs with an as lean a configuration as possible.


So when I added that option in the bootloader config, the system simply
failed to boot with the error message "dom0 kernel not specified. Check
bootloader configuration". This error message doesn't make any sense to
me since the only change that I did was adding the iommu=1 option. I
tried to add this option on several different locations on the arguments
line yielding this very same result. Removing this option makes the
system bootable again.


Sander Eikelenboom who is active on the xen-devel mailing list have
reported (on the Xen VTd HowTo page) IOMMU to work with this particular
motherboard. He was using a beta 1.75 revision of the BIOS firmware. I'm
currently using revision 1.9 so I'm considering to downgrade to the
older beta BIOS to see if that helps.


Robin.




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