[ipxe-devel] FATAL: int13_eltorito: call with AX=4d00. Please report

Shao Miller sha0.miller at gmail.com
Wed Jan 2 23:52:00 UTC 2013

On 1/2/2013 18:01, Michael Brown wrote:
> On Wednesday 02 Jan 2013 22:18:12 Michael Brown wrote:
>> When int13_load_mbr() fails (since drive 0xa0 does not have a valid MBR
>> present), we try int13_load_eltorito().  This issues INT 13,4d00 to read
>> the El Torito boot catalog, relying upon the BIOS to return with an error
>> if the drive isn't actually a CD-ROM.
>> I have no idea why VirtualBox would treat INT 13,4d00 on a non-CDROM drive
>> as being worthy of a fatal error.
> The attached patch adds a call to INT 13,4b01 to check that the drive is a CD-
> ROM before attempting to boot from it.  I have verified that this is sufficient
> to prevent the "FATAL: int13_eltorito: call with AX=4d00" error.
> It doesn't seem to be possible to use "sanboot --drive XX" to boot from the
> CD-ROM drive within VirtualBox; all drive numbers from 0x80 to 0xff return an
> error from INT 13,4b01.  It's possible that the VirtualBox BIOS doesn't bother
> setting up an INT 13 drive for the CD-ROM unless the BIOS is attempting a CD-
> ROM boot.
> Given that it seems to be impossible to use "sanboot --drive XX" in this way
> under VirtualBox, I'm not sure whether or not it's worth applying the patch.
> Thoughts?

D'oh.  I guess issuing our own INT 0x13, AH=0x4C would be too ugly?

- Shao Miller

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