Add "dis_ucode_ldr" to linux boot options for Recovery Mode

[Jeroen Bobbeldijk]

Thanks. I'll open a report for grub2.
According to the docs, dis_ucode_ldr is x86 only
(arch/x86/kernel/cpu/microcode/core.c), so my guess is that it will be
ignored for other architectures. According to the kernel code,
dis_ucode_ldr works for both AMD and Intel.
I have some time tomorrow on test this on a ARM device.

Jeroen

On Wed, Jun 5, 2019 at 7:49 PM Tyler Hicks <tyhicks at canonical.com> wrote:

> On 2019-06-05 10:03:06, Jeroen Bobbeldijk wrote:
> > Hi,
> >
> > Due to some recent problems with a microcode update which broke booting
> of
> > some laptops I suggest adding "dis_ucode_ldr" to recovery mode boot
> options
> > to allow booting after a bad microcode update.
> >
> > See the following topics that describe the problems:
> >  - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829620
> >  -
> https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/1
> >
> > When such problems occur it's very hard to see that the microcode loading
> > is the issue, the booting just hangs at the purple screen, even removing
> > "quiet splash" will not show the error.
>
> I really like this idea. Thanks for mentioning it.
>
> Please open a bug report here:
>
>  https://bugs.launchpad.net/ubuntu/+source/grub2/+filebug
>
> We'll need to double check that dis_ucode_ldr works as expected across
> all architectures. Otherwise, I can't think of any other technical
> blockers to doing this.
>
> Tyler
>
> >
> > Kind regards,
> >
> > Jeroen
>
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