[ipxe-devel] iPXE with Virtualbox

[Matthew Walster]

Apologies for not replying to the previous (small) thread regarding
this topic, I wasn't a subscriber back then.

iPXE doesn't work in Virtualbox, and it was suggested that someone run
through the "git bisect" procedure to find the commit. I've done so,
and git reports the following commit as the likely culprit:


6c35a525da16c6147600cd8613a9b60bb793b934 is the first bad commit
commit 6c35a525da16c6147600cd8613a9b60bb793b934
Author: Michael Brown <mcb30 at ipxe.org>
Date:   Mon Apr 19 22:22:11 2010 +0100

    [prefix] Use flat real mode for access to high memory

    Use flat real mode rather than 16-bit protected mode for access to
    high memory during installation.  This simplifies the code by reducing
    the number of CPU modes we need to think about, and also increases the
    amount of code in common between the normal and (somewhat
    hypothetical) KEEP_IT_REAL methods of operation.

    Signed-off-by: Michael Brown <mcb30 at ipxe.org>

:040000 040000 b4009d2b7e45222d34db4f466b89520c80d4d707
2a79c6844ccd8f7554636619abf65d67f8966ba2 M	src


I find it quite amusing that the preceding commit says:


    This change is unlikely to break anything, since any code that might
    potentially access beyond 64kB must use addr32 prefixes to do so; if
    this is the case then it is almost certainly code written to expect
    flat real mode anyway.


Oh well ;)

I'm not familiar enough with low-level coding to test further, but if
someone would like to give me further pointers I'd be glad to assist.

Matthew Walster