diff options
| author | Jan Kiszka <jan.kiszka@siemens.com> | 2012-02-01 20:31:41 +0100 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2012-02-17 09:58:22 -0600 |
| commit | ce967e2f33861b0e17753f97fa4527b5943c94b6 (patch) | |
| tree | 3f5c160e2b43162aa2dfda85eeb4813f20ebade4 /hw/hpet_emul.h | |
| parent | 319ba9f52737fc79de5c2c6abd059933398b72d5 (diff) | |
i8254: Rework & fix interaction with HPET in legacy mode
When the HPET enters legacy mode, the IRQ output of the PIT is
suppressed and replaced by the HPET timer 0. But the current code to
emulate this was broken in many ways. It reset the PIT state after
re-enabling, it worked against a stale static PIT structure, and it did
not properly saved/restored the IRQ output mask in the PIT vmstate.
This patch solves the PIT IRQ control in a different way. On x86, it
both redirects the PIT IRQ to the HPET, just like the RTC. But it also
keeps the control line from the HPET to the PIT. This allows to disable
the PIT QEMU timer when it is not needed. The PIT's view on the control
line state is now saved in the same format that qemu-kvm is already
using.
Note that, in contrast to the suppressed RTC IRQ line, we do not need to
save/restore the PIT line state in the HPET. As we trigger a PIT IRQ
update via the control line, the line state is reconstructed on mode
switch.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'hw/hpet_emul.h')
| -rw-r--r-- | hw/hpet_emul.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/hw/hpet_emul.h b/hw/hpet_emul.h index 6128702533..757f79fdd2 100644 --- a/hw/hpet_emul.h +++ b/hw/hpet_emul.h @@ -22,6 +22,9 @@ #define HPET_NUM_IRQ_ROUTES 32 +#define HPET_LEGACY_PIT_INT 0 +#define HPET_LEGACY_RTC_INT 1 + #define HPET_CFG_ENABLE 0x001 #define HPET_CFG_LEGACY 0x002 |