Re: USB device not seen by grub

[Vladimir 'φ-coder/phcoder' Serbinenko]

Robert Millan 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".
>
>   
It's by far not the same thing. EfiEmu emulates only RuntimeServices.
EFI has two types of functions: BootServices and RuntimeServices.
BootServices are only available when boot loader is running and are
terminated on kernel launch. RuntimeServices are always available but
have very small number of functions. And actually GRUB acts only as a
loader to efiemu??.o and real functions are contained in efiemu??.o
which is quite small
For BIOS disks emulations we would need much more functions but we could
adopt a similar approach. E.g:
bioshook usbbios.o <parameters>
chainloader (usb0,1)+1
usbbiso.o may of course be compiled from GRUB files but has to be
standalone. There are few tricky parts associated with this process but
basically it would be an overblown drivemap.

But I don't see any real reason to make even small fraction of required
effort since GRUB2 is able to load many free OS directly and so can load
them of an BIOS-invisible disks without any problems. Some free OS are
still out of GRUB family like Minix is but I would gladly accept a port
of it (which is orders of magnitude easier to do)
As of proprietary OS I think we need to support them only to the etent
of what they are able to do themselves. Documentation on such OS are
often scarce and anything we do may completely break with new version.
And all of this only to make good to someone who would like to see every
free software die?



-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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