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| author | H. Peter Anvin <hpa@zytor.com> | 2008-06-18 09:05:33 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2008-06-18 09:05:33 -0700 |
| commit | 34ffe9a0423644b7635683e462cab573f97ff255 (patch) | |
| tree | a186e5385fde63cf65453effb5446ef2c8513cb4 | |
| parent | 21edbdacf38c9eddc9dcca5c555a8a587f9df6fb (diff) | |
| download | syslinux-34ffe9a0423644b7635683e462cab573f97ff255.tar.gz | |
TEST: issue a null command to the KBC as part of A20-flippingsyslinux-3.70-pre19
UHCI supposedly wants a null command (0FFh) sent to the KBC as part of
the A20-flipping sequence. See if that works for us.
| -rw-r--r-- | core/bcopy32.inc | 18 | ||||
| -rw-r--r-- | memdisk/memdisk16.asm | 18 |
2 files changed, 32 insertions, 4 deletions
diff --git a/core/bcopy32.inc b/core/bcopy32.inc index 8f36d648..4ebbe3ca 100644 --- a/core/bcopy32.inc +++ b/core/bcopy32.inc @@ -413,7 +413,7 @@ a20_kbc: mov byte [cs:A20Type], A20_KBC ; Starting KBC command sequence - mov al,0D1h ; Command write + mov al,0D1h ; Write output port out 064h, al call empty_8042_uncond @@ -421,6 +421,13 @@ a20_kbc: out 060h, al call empty_8042_uncond + ; Apparently the UHCI spec assumes that A20 toggle + ; ends with a null command (assumed to be for sychronization?) + ; Put it here to see if it helps anything... + mov al,0FFh ; Null command + out 064h, al + call empty_8042_uncond + ; Verify that A20 actually is enabled. Do that by ; observing a word in low memory and the same word in ; the HMA until they are no longer coherent. Note that @@ -534,12 +541,19 @@ a20d_fast: ; a20d_kbc: call empty_8042_uncond + mov al,0D1h - out 064h, al ; Command write + out 064h, al ; Write output port call empty_8042_uncond + mov al,0DDh ; A20 off out 060h, al call empty_8042_uncond + + mov al,0FFh ; Null command/synchronization + out 064h, al + call empty_8042_uncond + ; Wait a bit for it to take effect a20d_snooze: push cx diff --git a/memdisk/memdisk16.asm b/memdisk/memdisk16.asm index 692ed8b8..d73ddc5d 100644 --- a/memdisk/memdisk16.asm +++ b/memdisk/memdisk16.asm @@ -294,7 +294,7 @@ a20_kbc: mov byte [A20Type], A20_KBC ; Starting KBC command sequence - mov al,0D1h ; Command write + mov al,0D1h ; Write output port out 064h, al call empty_8042_uncond @@ -302,6 +302,13 @@ a20_kbc: out 060h, al call empty_8042_uncond + ; Apparently the UHCI spec assumes that A20 toggle + ; ends with a null command (assumed to be for sychronization?) + ; Put it here to see if it helps anything... + mov al,0FFh ; Null command + out 064h, al + call empty_8042_uncond + ; Verify that A20 actually is enabled. Do that by ; observing a word in low memory and the same word in ; the HMA until they are no longer coherent. Note that @@ -424,12 +431,19 @@ a20d_fast: ; a20d_kbc: call empty_8042_uncond + mov al,0D1h - out 064h, al ; Command write + out 064h, al ; Write output port call empty_8042_uncond + mov al,0DDh ; A20 off out 060h, al call empty_8042_uncond + + mov al,0FFh ; Null command/synchronization + out 064h, al + call empty_8042_uncond + ; Wait a bit for it to take effect a20d_snooze: push cx |