diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2008-06-27 12:56:10 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2008-06-27 13:05:19 -0700 |
| commit | e41337a1383fed062e1f40789a60cebadde390b6 (patch) | |
| tree | 2c3e0943d47f779f611c61f5a968b6a024a60b69 /mbr | |
| parent | d132465e980db755312890dfbb98c8ed91d20245 (diff) | |
| download | syslinux-3.70-pre27.tar.gz | |
gPXE: [a20] Send a null command to the KBC after changing A20syslinux-3.70-pre27
Send a null command, specifically "pulse outputs" with no outputs
selected, to the KBC after changing A20. This was apparently done by
DOS, presumably as a synchronization hack, and the authors of the UHCI
spec thought it was inherent. Therefore, there are systems out there
(e.g. HP DL360 G5) which will stop responsing to "legacy USB" unless
they see the null command, 0xFF, written to port 0x64 at the end of
the A20 toggling sequence.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'mbr')
0 files changed, 0 insertions, 0 deletions