Re: [gentoo-user] CONFIG_IOMMU_SUPPORT???

[Mark Knecht <markknecht@gmail.com>]

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?

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.

Cheers,
Mark