[U-Boot] [PATCH 06/11] efi_loader: Decouple EFI input/output from stdin/stdout

[Rob Clark]

On Thu, Oct 12, 2017 at 9:11 AM, Alexander Graf <agraf at suse.de> wrote:
> On 10/12/2017 02:48 PM, Rob Clark wrote:
>>
>> On Thu, Oct 12, 2017 at 3:15 AM, Alexander Graf <agraf at suse.de> wrote:
>>>
>>>
>>> On 12.10.17 00:07, Rob Clark wrote:
>>>>
>>>> On Wed, Oct 11, 2017 at 10:45 AM, Alexander Graf <agraf at suse.de> wrote:
>>>>>
>>>>>
>>>>> On 10.10.17 14:23, Rob Clark wrote:
>>>>>>
>>>>>> In some cases, it is quite useful to have (for example) EFI on screen
>>>>>> but u-boot on serial port.
>>>>>>
>>>>>> This adds two new optional environment variables, "efiin" and
>>>>>> "efiout",
>>>>>> which can be used to set EFI console input/output independently of
>>>>>> u-boot's input/output.  If unset, EFI console will default to stdin/
>>>>>> stdout as before.
>>>>>>
>>>>>> Signed-off-by: Rob Clark <robdclark at gmail.com>
>>>>>
>>>>> With this patch, we lose the ability to have the efi in/out go to both
>>>>> graphical and serial console, right? This is critical functionality to
>>>>> have, since we don't necessarily know which output/input a user ends up
>>>>> using.
>>>>
>>>> I'll think about how to support iomux.. but some things like console
>>>> size are just not going to work properly there.  And as long as we fix
>>>
>>> Yeah, those probably would need to get special cased.
>>>
>>>> the stdout shenanigans (ie. what I was seeing w/ qemu-x86) you can
>>>> simply not set efiout var and have things working as before, so you
>>>> don't loose any existing functionality (although, like I said, if the
>>>> two different consoles have different sizes things aren't going to
>>>> work properly for anything other than simple cases).
>>>>
>>>> In most cases, the display driver should be able to detect whether a
>>>> display is connected.. this is what I've done on dragonboard410c, so
>>>> if no display plugged in, 'efiout=vidconsole' fails and you fall back
>>>> to serial, else you get efi on screen like you would on a "real"
>>>> computer.  For boards that have a display driver that isn't able to do
>>>> the basic check of whether a cable is plugged in, just don't set
>>>> "efiout" (or fix the display driver) ;-)
>>>
>>> Are you sure that's what happens on a "real" computer? As far as I
>>> remember from all ARM servers running edk2 based firmware that I've
>>> touched so far, the default is always to display on serial *and*
>>> graphical output at the same time.
>>
>> Well, I suppose some of the arm64 server vendors have done a better
>> job than others on firmware.. you'd hope they would probe EDID, and
>> report correct console dimensions based on display resolution, etc.
>
>
> Not sure that's terribly helpful. Most of these servers have built-in BMC
> chips that just go to a fake video console, so they always get EDID
> information, but that doesn't mean that it's sensible for what the user ends
> up seeing.
>
> I think what happens is that in most cases they just assume you have a 80x25
> console :).

oh, right.. BMC's..  well, let's not strive to be as horrible as
enterprise hardware ;-)

BR,
-R