Re: [Xen-devel] [PATCH v4 10/19] efi: move efi struct initialization to xen/common/lib.c

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.08.16 at 12:17, <daniel.kiper@xxxxxxxxxx> wrote:
> On Wed, Aug 17, 2016 at 09:56:39AM -0600, Jan Beulich wrote:
>> >>> On 06.08.16 at 01:04, <daniel.kiper@xxxxxxxxxx> wrote:
>> > A subsequent patch adds efi struct flags member which is used
>> > during runtime to differentiate between legacy BIOS and EFI
>> > platforms and multiboot2 and EFI native loader. So, efi symbol
>> > have to proper representation in ELF and PE Xen image. Hence,
>> > move efi struct initialization to xen/common/lib.c and remove
>> > efi symbol from ld script.
>> >
>> > Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
>> > ---
>> > v4 - suggestions/fixes:
>> >    - move efi struct initialization to xen/common/lib.c
>> >      and drop one from xen/arch/x86/efi/stub.c
>> >      (suggested by Jan Beulich),
>>
>> I recall I didn't like where you placed it last time round. I've just tried
>> to locate the old thread, but going back a whole year in the list archives
>> I was not able to find a mail with the title containing "move efi". Hence I
> 
> Here it is (I list just first email from thread in a given month):
>   https://lists.xen.org/archives/html/xen-devel/2016-04/msg02186.html 
>   https://lists.xen.org/archives/html/xen-devel/2016-05/msg02659.html 
>   https://lists.xen.org/archives/html/xen-devel/2016-06/msg00124.html 
>   https://lists.xen.org/archives/html/xen-devel/2016-07/msg00530.html 
> 
>> can only say what I think now, without reference to earlier remarks:
>> The struct currently isn't overly large, but I still don't see why non-EFI
>> builds need to include it instead of just the flags variable you mean to
>> introduce subsequently. And it's even less obvious what use it is on
>> platforms not even supporting EFI, i.e. ARM32.
> 
> I see two solutions for this issue:
>   - define efi struct members conditionally; this requires also
>     some #ifs sprinkled over Xen code (not very nice) or other
>     substantial changes,

That won't work, afaict, for the current model of building xen.efi
and xen.gz from mostly the same object files.

>   - replace efi.flags with efi_flags and leave existing code as is.
> 
> What is your choice?

Hence the latter would be my choice, unless you can give good
arguments in favor of another functioning solution.

Jan


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