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

[Juergen Gross <jgross@xxxxxxxx>]

On 06/02/18 17:53, Hans van Kranenburg wrote:
> On 02/06/2018 09:35 AM, Juergen Gross wrote:
>> 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.
> 
> Aha. Well, I can as well better jump to 4.15 now, since picking that
> patch on 4.14.17 shows I need more other patches it depends on, related
> to struct x86_legacy_features and x86_hyper_init reorganization.
> 
> So, I just built a 4.15.1 kernel (using gcc 7.2.0), which definitely has
> this one in it:
>   418492ba40b2 x86/virt/xen: Use guest_late_init to detect Xen PVH guest
> 
> I can boot via pvgrub2 (the Xen that's running now is current
> stable-4.10 plus the RSDP for PVH guest near 4GB patch).
> 
> But, it still tells me...
>   Booting paravirtualized kernel on Xen HVM
> 
> ...and then hangs somewhere halfway.
> 
> Full boot log here: http://paste.debian.net/plainh/ae3ea14b

You didn't add the RSDP detection patch, right? In the log I see:

ACPI BIOS Error (bug): A valid RSDP was not found (20170831/tbxfroot-244)


Juergen

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