Re: [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages

Borislav Petkov
2021-12-13T13:25:48Z

On Tue, Dec 07, 2021 at 11:16:31AM +0800, Baoquan He wrote:
> > This low 1M lock down is needed because AMD SME encrypts memory making
> > the old backup region mechanims impossible when switching into kdump
> > kernel. And Intel engineer mentioned their TDX (Trusted domain extensions)
> > which is under development in kernel also needs lock down the low 1M.
> > So we can't simply revert above commits to fix the page allocation
> > failure from DMA zone as someone suggested.

Did you read

f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM")

carefully for a more generically important reason as to why the first 1M
should not be used?

--
Regards/Gruss,
Boris.