Re: [PATCH 3/3] mini-os: fix number of pages for PVH

[Juergen Gross <jgross@xxxxxxxx>]

On 18.06.22 14:13, Samuel Thibault wrote:
> Hello,
>
> Juergen Gross, le sam. 18 juin 2022 12:48:16 +0200, a ecrit:
> > @@ -124,7 +126,7 @@ void arch_mm_preinit(void *p)
> >           do_exit();
> >       }
> >   
> > -    last_free_pfn = e820_get_maxpfn(ret);
> > +    last_free_pfn = e820_get_maxpfn(ret - e820_initial_reserved_pfns);
> Mmm, but the reserved pfn could be in the middle of the e820 address
> space.
That doesn't matter.

e820_get_maxpfn(n) will just return the pfn of the n-th RAM pfn it is
finding in the E820 map. This should be the last pfn with allocated
memory. Without subtracting the number of reserved pfns (which contain
normally memory which is allocated for the guest, but not usable as
RAM), Mini-OS tries to use RAM beyond its allocation, which fails.


Juergen

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature