Topic: How to add kernel parameters?

[holck]

With my HP Microserver, running SME 9, I always get the following message during boot:

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Jul  1 17:32:55 karoline kernel: Your BIOS doesn't leave an aperture memory hole
Jul  1 17:32:55 karoline kernel: Please enable the IOMMU option in the BIOS setup
Jul  1 17:32:55 karoline kernel: This costs you 64 MB of RAM
I found an advisory from HP
https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-a00022034en_us&docLocale=en_US
that recommends these parameters to be passed to the kernel during boot

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amd_iommo=on iommu=ptif you enable the BIOS IOMMU option.

How do I do that? I suppose, that if I just edit /boot/grub/grub.conf, the changes will be overwritten next time a new kernel is installed?

Thanks for a great distribution and a great community,
Jesper

[mmccarn]

There is a set of templates for /boot/grub/grub.conf in /etc/templates/boot/grub/grub.conf. 

The templates appear to be editing any existing /boot/grub/grub.conf -- so possibly edits made to grub.conf would be persistent.

I don't know what would happen when a new kernel is released - whether your customizations would be included for the new kernel, or left out.

As I read the HP advisory, if you turn on IOMMU the system won't even boot without the new paramaters - which makes this feel like a tricky proposition. 

[ReetP]

Try testing using edit/append in the boot menu to start with.

If it works then I believe you can edit grub.conf directly and your changes will be preserved across updates (do check this)

The only time it wouldn't be is if you did say a 'rescue' or possibly an upgrade to v10 when it occurs.

Yes, you could try adding a grub.conf template if you wanted but i don't think it is strictly necessary right now.

They templates are here:

/etc/e-smith/templates/boot/grub/grub.conf