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List:       grub-devel
Subject:    int13 drive emulation
From:       Giorgi Kvirkvia <kvirkvia () gmail ! com>
Date:       2013-03-28 18:14:49
Message-ID: CACbJNwVNvyzRQT4PWKjkF0Y9UcsP3JAC3GykOjPn397eAqP5zQ () mail ! gmail ! com
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Hi,

I wonder if it's possible to make a virtual INT13 drive which will be
internally driven by one  of grub's device drivers (I have USB in mind).
That would give potentially limitless power to user in terms of what to
chainload and where from.
That is definitely possible in general, Plop bootloader does it in
particular. I'm coming from userland coding so pardon my possible naivety,
but the only thing I can see which will interfere with that process, is
code being chainloaded overwriting grub's own, thus destroying running
driver/emulation code.

Can anybody confirm that it's possible or deny it? Some suggestions for
where to look for additional info on this case would be nice. I'm willing
to do actual coding, I just need some direction from more experienced
people in this kind of things.

P.S. I guess it's good idea to give you my reasoning behind what =E1=83=94=
=E1=83=AE=E1=83=90=E1=83=AA=E1=83=A2=E1=83=9A=E1=83=A7 I
want to do and why: I'm trying to boot Windows To Go installation from USB
drive on MacBookPro 8,2. MBP can EFI boot from USB, but Windows has trouble
with some devices when booted in that mode. Apparently MBP firmware applies
some tweaks to hardware in order to make them Windows-compatible. It boots
Windows in emulated BIOS mode while doing it. And because of the fact that
firmware for my particular MBP doesn't allow to boot in BIOS mode from
external drive, I installed Grub on local drive. It found USB drive without
any problems, but obviously it was unable to boot Windows USB.

Any help appreciated.

Giorgi

[Attachment #3 (text/html)]

<div dir="ltr">Hi,<div><br></div><div style>I wonder if it&#39;s possible to make a \
virtual INT13 drive which will be internally driven by one   of grub&#39;s device \
drivers (I have USB in mind). That would give potentially limitless power to user in \
terms of what to chainload and where from.</div>

<div style>That is definitely possible in general, Plop bootloader does it in \
particular. I&#39;m coming from userland coding so pardon my possible naivety, but \
the only thing I can see which will interfere with that process, is code being \
chainloaded overwriting grub&#39;s own, thus destroying running driver/emulation \
code.</div>

<div style><br></div><div style>Can anybody confirm that it&#39;s possible or deny \
it? Some suggestions for where to look for additional info on this case would be \
nice. I&#39;m willing to do actual coding, I just need some direction from more \
experienced people in this kind of things.</div>

<div style><br></div><div style>P.S. I guess it&#39;s good idea to give you my \
reasoning behind what ეხაცტლყ I want to do and why: I&#39;m trying to \
boot Windows To Go installation from USB drive on MacBookPro 8,2. MBP can EFI boot \
from USB, but Windows has trouble with some devices when booted in that mode. \
Apparently MBP firmware applies some tweaks to hardware in order to make them \
Windows-compatible. It boots Windows in emulated BIOS mode while doing it. And \
because of the fact that firmware for my particular MBP doesn&#39;t allow to boot in \
BIOS mode from external drive, I installed Grub on local drive. It found USB drive \
without any problems, but obviously it was unable to boot Windows USB.</div>

<div style><br></div><div style>Any help appreciated.</div><div style><br></div><div \
style>Giorgi</div></div>



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