[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Loading a 32 bit kernel from 64 bit grub-xen




On 1 Jul 2014 20:28, "Phillip Susi" <psusi@xxxxxxxxxx> wrote:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 7/1/2014 12:18 PM, Andrey Borzenkov wrote:
> > Ð Tue, 01 Jul 2014 12:06:08 -0400 Phillip Susi <psusi@xxxxxxxxxx>
> > ÐÐÑÐÑ:
> >
> >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
> >
> >> I have been trying to fix grub to load a 32 bit kernel from the
> >> 64 bit xen build. ÂAfter fixing up one or two minor issues with
> >> the elf loader, I believe I now have it to the point where it
> >> jumps correctly to the 32 bit kernel and it crashes there, since
> >> it is 32 bit code still executing on a cpu in 64 bit mode. ÂThe
> >> question is how to return the cpu to 32 bit mode *under xen*?
> >
> >
> > IIRC it was already discussed not long ago and it seems to be Xen
> > limitation. You probably need to ask on xen-devel to be sure.
> >
> > Is it not more simple to use 32 bit grub with 32 bit kernel to
> > start with?
>
> The problem with that is that you have to know in advance which kernel
> you are going to boot. ÂThat makes configuring virtual hosts harder;
> they just want one grub image they can use to chainload whatever the
> guest wants to install in their domain.
>
> Also there must be a way to do this otherwise a 64 bit kernel running
> under xen wouldn't be able to execute a 32 bit binary.
Binaries don't have to use e.g. paging table or hypercall mechanism. You need to either make xen switch all those structures or port kernels to fake-32-xen mode. When either is done GRUB part will be trivial but either of those tasks is outside of grub scope.
>ÂI suppose I'll
> Cc xen-devel.
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v2.0.17 (MingW32)
> Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
>
> iQEcBAEBAgAGBQJTsv2uAAoJEI5FoCIzSKrwvQQIAIZ/ipl4MRQcf2nhOBUFzEzM
> WTNx4ul/ZAtEDATMpokIpnhZuU1VDqzeOHbHZDXQfXZbYyhHM5LTKqiCLEGW0qnE
> Q+qW5Q9cKeXolx/hjZ4FrUU1fMHZ9tZ7dhb68iB1aGELZVtR7yXJFsl+4ZF6LPvN
> 5/w3g6WAd4fWpfEswL34EzaUW0RAfa0O4xmgHbQkkXftO1TLOoiswwGcW3xc9nai
> jr03H9NyOUTgZX89xhR/LAKuCMivs/FWARQ1UDMwy9KfY0IIoka94BfL36T4te01
> HrYmiXtKoiaOZ0IyEhm5HY+X7bHBZU/eycQ3KdRG8aW694Y0zrCEEKhw0pJpbw0=
> =Vadi
> -----END PGP SIGNATURE-----
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@xxxxxxx
> https://lists.gnu.org/mailman/listinfo/grub-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.