The reset requested via the keyboard controller (port 0x64) is actually a
soft reset, but qemu has supported it since forever (plus qemu has not
distinguished between hard reset and soft reset, although this is changing
now). Therefore leave the current IoWrite() in place for compatibility.
On qemu versions with commit 1ec4ba74 ("PIIX3: reset the VM when the Reset
Control Register's RCPU bit gets set"), use the PIIX3 RCR as first choice.
In the future qemu will act differently on soft vs. hard reset requests,
and we should honor that in ResetCold().
Writing to ioport 0xCF9 on qemu builds prior to commit 1ec4ba74 should
have no effect. Access to the PCI host config register went through
several implementations in qemu. Commit 9f6f0423 ("pci_host: rewrite
using rwhandler") seems safe, both before and after.
Commit d0ed8076 ("pci_host: convert conf index and data ports to memory
API") inadvertently dropped the alignment/size check, causing a boot
regression on NetBSD. It was fixed about six months later in commit
cdde6ffc, which is current. Translating that to qemu releases, the bug
was visible from v1.0 to v1.1.0.
On physical hardware cycling between reset methods is sometimes necessary
<http://mjg59.dreamwidth.org/3561.html>. On qemu the port access should
trap immediately.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <[email protected]>
---
OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
b/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
index 52406ad..85af7f1 100644
--- a/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
+++ b/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
@@ -45,7 +45,8 @@ ResetCold (
VOID
)
{
- IoWrite8 (0x64, 0xfe);
+ IoWrite8 (0xCF9, BIT2 | BIT1); // 1st choice: PIIX3 RCR, RCPU|SRST
+ IoWrite8 (0x64, 0xfe); // 2nd choice: keyboard controller
}
/**
--
1.7.1
------------------------------------------------------------------------------
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