Commit 238050d ("[build] Work around bug in gcc >= 4.8") works around
one instance of a bug in recent versions of gcc, in which "ebp" cannot
be specified within an asm clobber list.
Some versions of gcc seem to exhibit the same bug on other points in
the codebase. Fix by changing all instances of "ebp" in a clobber
list to use the push/pop %ebp workaround instead.
Originally-implemented-by: Víctor Román Archidona <contacto@victor-roman.es>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit 73eb3f1 ("[int13] Zero all possible registers when jumping to a
boot sector") introduced a regression preventing the SAN-booting of
boot sectors which rely upon %dl containing the correct drive number
(such as most CD-ROM boot sectors).
Fix by not zeroing %edx.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
At least one boot sector (the DUET boot sector used for bootstrapping
EFI from a non-EFI system) fails to initialise the high words of
registers before using them in calculations, leading to undefined
behaviour.
Work around such broken boot sectors by explicitly zeroing the
contents of all registers apart from %cs:%ip and %ss:%sp.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
