linux-kernel - Re: [PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

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Message-ID: <0d04d8cd-41e6-31bd-f5e6-8d1f6fd60efb@suse.com>
Date:   Wed, 8 Nov 2017 14:40:57 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        pbonzini@...hat.com, rkrcmar@...hat.com, rjw@...ysocki.net,
        len.brown@...el.com, pavel@....cz
Subject: Re: [PATCH 0/3] x86/xen: support booting PVH guest via standard boot
 path

On 08/11/17 14:37, Boris Ostrovsky wrote:
> On 11/08/2017 04:07 AM, Juergen Gross wrote:
>> Booting a Xen PVH guest requires a special boot entry as it is
>> mandatory to setup some Xen-specific interfaces rather early. When grub
>> or OVMF are used as boot loaders, however, those will fill the boot
>> parameters in zeropage and there is no longer a need to do something
>> PVH specific in the early boot path.
>>
>> This patch series adds support for that scenario by identifying PVH
>> environment and doing the required init steps via Xen hooks instead of
>> using a dedicated boot entry.
>>
>> The dedicated entry is still needed for support of Dom0 running in PVH
>> mode as in this case there is no grub or OVMF involved for filling in
>> the boot parameters.
> 
> We are going to continue supporting direct boot of unprivileged guests
> too so this entry point will be needed not for dom0 only.

Sure, but using e.g. grub in this case would be an alternative. For Dom0
this alternative isn't existing. So this entry is mandatory, not a "nice
to have".


Juergen