On Mon, Feb 15, 2016 at 01:07:09AM +0000, Michael Brown wrote:
On 14/02/16 19:52, Michael S. Tsirkin wrote:
On Sun, Feb 14, 2016 at 05:36:38PM +0000, Michael Brown wrote:
On 14/02/16 15:53, Michael S. Tsirkin wrote:
do you think %DS should be zeroed when NBP is called then?
Not according to the PXE spec.
As far as I can tell, the initial value of %ds is undefined for both a PXE NBP and a BIOS boot sector.
Thanks,
Out of interest: did this question arise as a purely academic curiosity, or is there some product in existence which creates a boot sector that relies on %ds==0?
Michael
FWIW QEMU has a unit test with a boot sector that relies on %ds=0: https://git.kernel.org/cgit/virt/kvm/mst/qemu.git/tree/tests/bios-tables-tes... (search for boot_sector in this file).
It's a test, not a product though, and would be easy to change not to rely on this.