linux-kernel - RE: [PATCH v5 05/16] x86/cpu: Defer CR pinning setup until after EFI initialization

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Message-ID: <SJ1PR11MB6083CA923D92CD70AE6C5FB9FC4B2@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Tue, 29 Oct 2024 22:59:25 +0000
From: "Luck, Tony" <tony.luck@...el.com>
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Subject: RE: [PATCH v5 05/16] x86/cpu: Defer CR pinning setup until after EFI
 initialization

> *IF* we switched things to do text poking in the upper half of the
> address space, we'd probably want to find a completely unused PGD entry.
>  I'm not sure off the top of my head if we have a good one for that or
> if it's worth the trouble.

I expect that would be easy on 64-bit (no way the kernel needs all the
PGD entries from 256..511) but hard for 32-bit (where kernel address
space is in critically short supply on any machine with >1GB RAM).

-Tony