Re: [gentoo-user] CONFIG_IOMMU_SUPPORT???

[Hilco Wijbenga <hilco.wijbenga@gmail.com>]

On 24 August 2011 10:55, Mark Knecht <markknecht@gmail.com> wrote:
> On Tue, Aug 23, 2011 at 9:18 PM, Hilco Wijbenga
> <hilco.wijbenga@gmail.com> wrote:
>> On 23 August 2011 20:38, Mark Knecht <markknecht@gmail.com> wrote:
>>> Hi all,
>>>   Can someone point me toward somehow enabling CONFIG_IOMMU_SUPPORT?
>>> It is apparently a kernel config option no required by
>>> virtualbox-drivers but I'm not finding it in the 3.0.3 kernel. I
>>> suspect there's something else I need to enable before this option
>>> becomes available? Unfortunately I haven't been able to Google what I
>>> need to do to find it.
>>>
>>> Thanks,
>>> Mark
>>>
>>> * Messages for package app-emulation/virtualbox-modules-4.1.2:
>>>
>>>  *   CONFIG_IOMMU_SUPPORT:       is not set when it should be.
>>>  * Please check to make sure these options are set correctly.
>>>  * Failure to do so may cause unexpected problems.
>>> <SNIP>
>>>
>>> k2 linux # cat .config | grep IOMMU
>>> CONFIG_GART_IOMMU=y
>>> # CONFIG_CALGARY_IOMMU is not set
>>> CONFIG_AMD_IOMMU=y
>>> # CONFIG_AMD_IOMMU_STATS is not set
>>> CONFIG_IOMMU_HELPER=y
>>> CONFIG_IOMMU_API=y
>>> # CONFIG_IOMMU_DEBUG is not set
>>> # CONFIG_IOMMU_STRESS is not set
>>> k2 linux #
>>
>> I noticed the same. There does not appear to be any such option but
>> luckily its absence does not appear to affect running VB at all.
>>
>
> At the time of writing this I haven't tried Gregory's item about the
> CONFIG_CALGARY_IOMMU option. I'll try that later when I get to the
> machine but the reading I did on the web sounded like that was for IBM
> specific hardware.
>
> Here it seems that on the machine I was working - Intel based, i920 -
> VB won't install Win 7 64-bit without it. I get a bunch of messages
> that it will install but many cause problems. Are you running any
> 64-bit VMs?

Sort of. I'm working on installing Gentoo AMD64 in a VB machine. No
problems so far but I've only just started (it's a weekend project).
Certainly no Windows.

> However I've got another Intel machine where I can install Win 7
> 64-bit in VB just fine with no complaints at all. Here's the IOMMU
> stuff from that box:
>
> mark@c2stable ~ $ uname -a
> Linux c2stable 3.0.1-gentoo #1 SMP PREEMPT Mon Aug 8 13:05:19 PDT 2011
> x86_64 Intel(R) Core(TM) i7 CPU X 980 @ 3.33GHz GenuineIntel GNU/Linux
> mark@c2stable ~ $ zcat /proc/config.gz | grep IOMMU
> CONFIG_GART_IOMMU=y
> # CONFIG_CALGARY_IOMMU is not set
> # CONFIG_AMD_IOMMU is not set
> CONFIG_IOMMU_HELPER=y
> CONFIG_IOMMU_API=y
> # CONFIG_IOMMU_DEBUG is not set
> # CONFIG_IOMMU_STRESS is not set
> mark@c2stable ~ $
>
> Except for the AMD option they seem identical unless I'm misreading something.
>
> I'm now wondering if there is both a BIOS and chipset component to
> making this work? I'm pretty sure I've got all the Vt-d stuff enabled
> but I'll have to wait to go into BIOS on both of them to compare.
>
> I'll try to do a diff later today between both machine's .config files
> to look for differences.

Can't you simply install the Calgary IOMMU as well? I know that it
seems IBM based stuff (I noticed it myself when I was going through
the same process) which you probably do not need but I assume it can't
hurt (apart from making the kernel a bit bigger). But if it fixes your
problem... Probably worth a try.