Re: [Xen-users] pvgrub2(-like?) booting methods for PVHv2 guests

[Juergen Gross <jgross@xxxxxxxx>]

On 05/02/18 20:49, Hans van Kranenburg wrote:
> On 01/25/2018 03:31 PM, Juergen Gross wrote:
>> On 25/01/18 15:12, Hans van Kranenburg wrote:
>>> On 01/25/2018 02:46 PM, Hans van Kranenburg wrote:
>>>> On 25/01/2018 13:29, Juergen Gross wrote:
>>>>> On 25/01/18 13:19, Andy Smith wrote:
>>>>>> Hi Hans,
>>>>>>
>>>>>> On Thu, Jan 25, 2018 at 12:39:56PM +0100, Hans van Kranenburg wrote:
>>>>>>> And now I get console output and things happen. Only it can't find the 
>>>>>>> disk.
>>>>>>
>>>>>> I was trying similar thing (4.10 and PVH) and also ended up with a
>>>>>> guest with no block devices. I reported this on grub-devel:
>>>>>>
>>>>>>     <http://lists.gnu.org/archive/html/grub-devel/2018-01/msg00018.html>
>>>>>>
>>>>>> as I was thinking this was not a Xen problem since same thing boots
>>>>>> okay outside grub with direct kernel boot.
>>>>>>
>>>>>> Juergen did reply and said I needed this kernel patch in the guest:
>>>>>>
>>>>>>     <https://lists.xen.org/archives/html/xen-devel/2017-11/msg01681.html>
>>>>>>
>>>>>> But I think you have this don't you?
>>>>
>>>> Yes, see my earlier mail with all the steps that I did, step 6.
>>>>
>>>>> As the ACPI tables are found, I'd say yes. :-)
>>>>
>>>> dmesg output is pretty different when I boot directly with the kernel
>>>> and initrd copied on the dom0.
>>>>
>>>> Remember, it's the same kernel/initrd, and without grub in between it
>>>> boots with all vcpus network and disk.
>>>>
>>>> With grub in between, this at least does look suspicious:
>>>>
>>>> [    0.032110] PCI: System does not support PCI
>>>
>>> Eh, that's in both, stay awake Hans.
>>>
>>>> And yes, there are also no successful netfront lines.
>>>>
>>>> Without grub: http://paste.debian.net/plainh/7120cef2
>>>> With grub: http://paste.debian.net/plainh/426bed60
>>>
>>> Or the diff between them, which shows what changes when inserting grub
>>> in between:
>>>
>>> http://paste.debian.net/plainh/52b2d618
>>>
>>> I must admit I don't know too much (yet) about all those changed lines,
>>> but this next is also a very interesting change?...
>>>
>>> -Booting paravirtualized kernel on Xen PVH
>>> +Booting paravirtualized kernel on Xen HVM
>>
>> Aah, yes, this should be the reason for the problems.
>>
>> I addressed the ACPI problem first. What is missing now is to set PVH
>> mode when booting via grub.
>>
>> So please stay tuned...
> 
> For my info... Is this something like flipping a bit somewhere, or will
> it involve a whole lot more complicated wizardry?
> 
> Real question is of course if there's a PoC solution to apply that I can
> use now? ;-] I'm throwing custom build kernels at my test environment,
> and if I could save the time (and mistakes) of manually editing the
> guest files and instead hit the pvgrub2+PVHv2 path many times to test...

So I looked into this briefly and discovered that my memory really needs
the backup I have on my hard disk: you want commit
418492ba40b2c2bbdaf1a169aac5b1673bde8189 which was for 4.15.


Juergen

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