On 02/22/2013 03:04 PM, Reindl Harald wrote:
>
> Am 22.02.2013 20:58, schrieb Robert Moskowitz:
>> Kernel param. I really should have caught that.
>>
>> So I was all ready to edit grub.conf and then slapped my hand.
>> You TEST it out first, adding the command at boot time. ARGH!
> one option
>
>> Once before (5+ years back) I had to add a kernel param and did it wrong and
>> it was a big recovery challenge
> what is the challenge?
> there is no difference add or remove a param at boot
If you get the option wrong and the system will now not boot? Then you
have to boot from a recovery CD, mount your harddrve /boot and edit out
the change from grub.conf and try again. All the time you SHOULD have
been working on something else.
>
>> But as I read up on this option, it does not sound like something I want
>> to globally turn off just to stop a supposedly annoying
>> message (if they have indeed worked around it, and my new DNS server is running with this OK)
> and you looked at the other options?
> "intel_iommu=igfx_off" maybe a good idea
>
> intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
> on
> Enable intel iommu driver.
> off
> Disable intel iommu driver.
> igfx_off [Default Off]
> By default, gfx is mapped as normal device. If a gfx
> device has a dedicated DMAR unit, the DMAR unit is
> bypassed by not enabling DMAR with this option. In
> this case, gfx device will use physical address for
> DMA.
> forcedac [x86_64]
> With this option iommu will not optimize to look
> for io virtual address below 32 bit forcing dual
> address cycle on pci bus for cards supporting greater
> than 32 bit addressing. The default is to look
> for translation below 32 bit and if not available
> then look in the higher range.
> strict [Default Off]
> With this option on every unmap_single operation will
> result in a hardware IOTLB flush operation as opposed
> to batching them for performance.
> sp_off [Default Off]
> By default, super page will be supported if Intel IOMMU
> has the capability. With this option, super page will
> not be supported.
>
I will look at these closely and figure out what course to test. The
sabbath is almost here, so got a hard stop time.
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