Re: Dell Media Direct button

[Javier Martín]

2008/8/20 Colin D Bennett <address@hidden>:
> On Wed, 20 Aug 2008 12:12:59 +0200
> Robert Millan <address@hidden> wrote:
>
>> On Wed, Aug 20, 2008 at 10:57:22AM +0200, Per Öberg wrote:
>> > Hi
>> >
>> > Some laptops, e.g., from Dell have a special button that they use to
>> > boot a special embedded OS for media only instead of the ordinary
>> > OS.
>> >
>> > For my Dell XPS1330M I can determine if the Media button was
>> > pressed by first writing 0xf9 to port 0x70 and then testing bit
>> > 0x08 of port 0x71.
>> >
>> > It would be really nice if such a test could be enabled in grub so
>> > that grub can go directly to a specific menu alternative without
>> > showing the gui if the media button was pressed.
>> >
>> > Is this interesting? I'd like to contribute but I don't know where
>> > to start.
>>
>> Sounds interesting, but this needs some thought on how to design it.
>>
>> I suppose what you want is change the 'default' variable.  Perhaps
>> increase it by 1?  But then, where do you do this?  grub_machine_init
>> is too early as 'default' hasn't been set yet.
>>
>> Maybe we could have a global 'int default_offset' variable that is
>> initialized in grub_machine_init and later on used by normal.mod?
>
> If I pressed the "Media Direct" button, I would also want to have a
> timeout of 0, since by pressing the Media Direct button instead of the
> power button, I've already indicated which entry I want to boot, and
> there is no need to show the menu -- unless, perhaps, we decided to
> show a different "media" menu... so hopefully giving all the power to
> the grub.cfg script would be enough to make all this possible.
>
> Regards,
> Colin
>
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>
>

Well, I own a XPS1330 myself (I'm writing from it now, as I'm taking a
week at the beach in Benidorm ^^). This functionality could be
implemented by a module that used the pre-menu hooks proposed by Bean:
it would check the status before the menu is shown, then act on the
result.

However, all this assumes that pressing that key creates no additional
side effect like the replacement of the MBR by the system firmware,
booting another MBR written in flash memory or something like that: I
thought the choice took place at the "real" MBR, but disassembling it
revealed that it does not use the mentioned I/O ports interface, so
most likely what the system firmware does is set the active flag in
the MediaDirect partition.

I'm ready to check any related patches on the actual hardware _once
I'm back in Madrid_ because here I have no recovery tools.

-Habbit