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Re: QEMU and ElTorito and EDD 3

From: Vesa Jääskeläinen
Subject: Re: QEMU and ElTorito and EDD 3
Date: Wed, 13 Jun 2007 17:56:04 +0300
User-agent: Thunderbird (Windows/20070326)

Alex Roman wrote:
> On 13/06/07, Alex Roman <address@hidden> wrote:
>> However, it does not support ElTorito extensions... I called the 4D
>> function (Return Boot Catalog) and the QEMU BIOS (I think) printed a
>> "nice" informative message:
>> "FATAL: Int13 eltorito call with AX=4D00. Please report" (see screenshot)
> Furthermore, I wonder... If QEMU doesn't support this, and installing
> Windows and other operating systems off CDs works, will many BIOSes
> support this interface at all? PHOENIX BIOSes should, IMO, since the
> ElTorito standard is made by PHOENIX, but what about the others?
> We might have to read the boot catalog manually, not with the 4Dh
> function to achieve more compatibility. Tonight I'll try to do an
> "Extended Read", function 42h, to get the boot catalog and parse it in
> a structure and see if it "makes sense".

El Torito part of the EDD3 spec might not be accessible if you have not
booted with such media that needs that support. At least this seems to
be case with VMWare which uses Phoenix BIOS. I once tested out those
CD-ROM access API's, but problem is that those devices are not exposed
by BIOS when booted from floppy or from HDD. Eg. when you enumerate all
devices, CD-ROM drives are not listed at all thus cannot be accessed.

But then again... I noticed that your device id was 0xe0 which I think I
may have not tried out. I had much better success with directly using ATA :)

If you have floppy image, I can try it out in VMWare and tell results
what happens.

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