Re: [Xen-devel] Xen 4.12 panic on Thinkpad W540 with UEFI mutiboot2, efi=no-rs workarounds it

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.10.2019 13:52, Marek Marczykowski-Górecki  wrote:
> On Wed, Oct 09, 2019 at 01:48:38PM +0200, Jan Beulich wrote:
>> On 09.10.2019 13:00, Marek Marczykowski-Górecki  wrote:
>>> On Wed, Oct 09, 2019 at 12:50:09PM +0200, Jan Beulich wrote:
>>>> On 09.10.2019 12:31, Marek Marczykowski-Górecki  wrote:
>>>>> BTW How runtime services work after kexec? I don't see EFI handles
>>>>> handed over kexec, are they somehow re-discovered?
>>>>
>>>> What EFI handles are you talking about? For runtime services
>>>> what a consumer needs is a table pointer, which is a field
>>>> in the system table, which in turn is an argument passed to
>>>> the EFI application's entry point.
>>>
>>> Yes, I'm talking about those pointers (system table specifically).
>>>
>>>> I didn't think there are
>>>> provisions in the spec for either of these pointers being NULL.
>>>
>>> But I don't see kexec using EFI application entry point. Am I missing
>>> something?
>>
>> Can we stop thinking about a Linux -> Xen transition on this
>> thread please? 
> 
> I'm talking about Xen->Xen transition here. How system table pointer is
> passed from old Xen to new Xen instance? And how the new Xen instance
> deals with boot services being not available anymore?

It doesn't. I should better have said "* -> Xen transitions" in
my earlier reply. I simply can't see how this can all work with
EFI underneath without some extra conveying of data from the old
to the new instance.

Jan

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