Re: [Xen-devel] [PATCH v3 13/16 - RFC] x86: add multiboot2 protocol support for EFI platforms

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.06.16 at 18:12, <daniel.kiper@xxxxxxxxxx> wrote:
> On Thu, Jun 02, 2016 at 02:34:28AM -0600, Jan Beulich wrote:
>> >>> On 01.06.16 at 21:03, <daniel.kiper@xxxxxxxxxx> wrote:
>> > Hence, we are not able to get anything from EFI. Latter
>> > means that we were booted via older multiboot2 version which shutdown
>> > boot services.
>>
>> Hmm, that's certainly one of the possibilities, yes. I wonder then
>> whether we wouldn't better do away with all of those output
>> attempts then.
> 
> This is one option. However, IMO, not nice. Maybe we should stay with
> serial plus VGA on legacy BIOS platforms. Serials looks quite well
> defined even on EFI platforms. However, if it is not available x86
> out instruction should not do any harm. Though if we wish to increase
> chance of reaching interested parties I would send error messages to
> 0x3f8 and 0x2f8 at once. AFAICT, on many machines usually at least one
> if not both standard/legacy serial ports are available.

On many _older_ machines you mean. Any new machines I got
hold of in the last couple of years didn't have any serial ports
anymore (some still have them implemented in the LPC, but not
wired through, but legacy free systems wouldn't have them at all
anymore).

Jan


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