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Re: [MINI-OS PATCH v2 1/2] mm: provide a way to do very early page table allocations
- To: Juergen Gross <jgross@xxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 29 Jul 2025 10:52:54 +0200
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- Cc: samuel.thibault@xxxxxxxxxxxx, minios-devel@xxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 29 Jul 2025 09:01:33 +0000
- List-id: Mini-os development list <minios-devel.lists.xenproject.org>
On 29.07.2025 10:38, Juergen Gross wrote:
> --- a/arch/x86/mm.c
> +++ b/arch/x86/mm.c
> @@ -640,13 +640,20 @@ void change_readonly(bool readonly)
> /*
> * return a valid PTE for a given virtual address. If PTE does not exist,
> * allocate page-table pages.
> + * Provide a small pool for allocating some page tables very early. Those are
> + * needed currently for mapping the shared info page, so 2 pages ought to be
> + * enough. Add one spare page anyway.
> */
Hmm, 2 pages plus one spare doesn't yield ...
> +static char early_pt[4][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
... 4. Was 2 a typo, and 3 was meant? (Which, just to mention it, then isn't
correct for 32-bit aiui.) Whatever adjustment wants making - happy to do so
while committing. Just need to know which way. Then
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Jan
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