Re: USB device not seen by grub

[address@hidden]

On Fri, Dec 4, 2009 at 3:36 PM, Robert Millan <address@hidden> wrote:
> On Thu, Dec 03, 2009 at 06:27:07PM -0600, address@hidden wrote:
>> 2009/12/3 Vladimir 'φ-coder/phcoder' Serbinenko <address@hidden>:
>> > Chris Jones wrote:
>> >> I am trying to have grub boot off a partition on a USB stick.
>> >>
>> >>
>> > You can't chainload to disk invisible by BIOS. But you can load
>> > supported OSes from it.
>>
>> What would be necessary to enable chainload to such devices?  Install
>> an IRQ 19 handler?
>
> Yeah, something like that.  In essence, GRUB acting as a BIOS.  Sounds awful,
> but hey we already have "efiemu".

As Vladimir says, the legacy grub "map" command must already be
installing such a hook (although it proxies implementation to the
existing BIOS after changing the drive number, rather than calling a
grub storage driver).

>
>> Invoke the extension ROM of the host adapter so
>> that it hooks IRQ 19?
>
> There's usually no such ROM.  Except for adapters that come in discrete
> PCI cards.  And even then, I doubt it's always present.

There are actually quite a lot of devices like this.  Most notebooks
have broken BIOS that won't load the extension ROM from a PCMCIA slot,
if grub could do so it would enable booting from a wide variety of
PCMCIA/CardBus/ExpressCard-to-SCSI/SATA/USB adapters.

Here's one example that I happen to own, and got frustrated with
system BIOS not allowing boot from expansion card:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820161325&cm_re=SolidGO-_-20-161-325-_-Product

I'm fairly sure there is an extension BIOS because some people report
being able to boot from it, however most laptops cannot.

>
> --
> Robert Millan
>
>  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
>  how) you may access your data; but nobody's threatening your freedom: we
>  still allow you to remove your data and not access it at all."
>
>
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