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From: =?windows-1252?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
Subject: Re: [PATCH v3 00/32] Introduce HVM without dm and new
 boot ABI
Date: Fri, 3 Jul 2015 18:36:37 +0200
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To: David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org
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El 03/07/15 a les 18.19, David Vrabel ha escrit:
> On 03/07/15 12:34, Roger Pau Monne wrote:
>>
>> And for the FreeBSD part:
> 
> Have you thought at all about what the Linux support for this mode would
> look like?
> 
> I started briefly looking today but don't really have time to look into
> it properly.  I do think we want to use as much of the native/HVM code
> as possible and avoid the PV path (the current Linux PVH code uses too
> much of the PV entry point, IMO).

I'm afraid I'm not that familiar with the native Linux entry point in
order to know how much of that can be reused. Does the amd64 kernel
contain a 32bit entry point or the kernel is expected to be launched in
long mode with some page tables already setup?

Iff Linux on i386/amd64 already contains a 32bit protected mode without
paging entry point then I guess most of the code can be reused.

Note that FreeBSD/amd64 didn't have any of this (the kernel is launched
in long mode with some initial page tables setup by the loader), so the
code needed for Linux should be similar to the one on FreeBSD or even
less if there's an entry point that we can reuse:

http://xenbits.xen.org/gitweb/?p=people/royger/freebsd.git;a=blob;f=sys/amd64/amd64/xen-locore32.S;h=fd73d150009ab21059d4df219e6a62cc40d5994e;hb=refs/heads/new_entry_point_v2

Roger.