On 27.12.2010 04:51, Stefan Hajnoczi wrote:
On Sun, Dec 26, 2010 at 9:21 PM, Peter Lieven<pl@xxxxxxx> wrote:
Am 25.12.2010 um 20:02 schrieb Peter Lieven:
Am 23.12.2010 um 03:42 schrieb Stefan Hajnoczi:
On Wed, Dec 22, 2010 at 10:02 AM, Peter Lieven<pl@xxxxxxx> wrote:
If I start a VM with the following parameters
qemu-kvm-0.13.0 -m 2048 -smp 2 -monitor tcp:0:4014,server,nowait -vnc :14 -name 'ubuntu.test' -boot order=dc,menu=off -cdrom ubuntu-10.04.1-desktop-amd64.iso -k de
and select memtest in the Ubuntu CD Boot Menu, the VM immediately resets. After this reset there happen several errors including graphic corruption or the qemu-kvm binary
aborting with error 134.
Exactly the same scenario on the same machine with qemu-kvm-0.12.5 works flawlessly.
Any ideas?
You could track down the commit which broke this using git-bisect(1).
The steps are:
$ git bisect start v0.13.0 v0.12.5
Then:
$ ./configure [...]&& make
$ x86_64-softmmu/qemu-system-x86_64 -m 2048 -smp 2 -monitor
tcp:0:4014,server,nowait -vnc :14 -name 'ubuntu.test' -boot
order=dc,menu=off -cdrom ubuntu-10.04.1-desktop-amd64.iso -k de
If memtest runs as expected:
$ git bisect good
otherwise:
$ git bisect bad
Keep repeating this and you should end up at the commit that introduced the bug.
this was the outcome of my bisect session:
956a3e6bb7386de48b642d4fee11f7f86a2fcf9a is first bad commit
commit 956a3e6bb7386de48b642d4fee11f7f86a2fcf9a
Author: Blue Swirl<blauwirbel@xxxxxxxxx>
Date: Sat May 22 07:59:01 2010 +0000
Compile pckbd only once
Use a qemu_irq to indicate A20 line changes. Move I/O port 92
to pckbd.c.
Signed-off-by: Blue Swirl<blauwirbel@xxxxxxxxx>
:100644 100644 acbaf227455f931f3ef6dbe0bb4494c6b41f2cd9 1a33d4eb4a5624c55896871b5f4ecde78a49ff28 M Makefile.objs
:100644 100644 a22484e1e98355a35deeb5038a45fb8fe8685a91 ba5147fbc48e4faef072a5be6b0d69d3201c1e18 M Makefile.target
:040000 040000 dd03f81a42b5162c93c40c517f45eb9f7bece93c 309f472328632319a15128a59715aa63daf4d92c M default-configs
:040000 040000 83201c4fcde2f592a771479246e0a33a8906515b b1192bce85f2a7129fb19cf2fe7462ef168165cb M hw
bisect run success
I tracked down the regression to a bug in commit 956a3e6bb7386de48b642d4fee11f7f86a2fcf9a
In the patch the outport of the keyboard controller and ioport 0x92 are made the same.
this cannot work:
a) both share bit 1 to enable a20_gate. 1=enable, 0=disable -> ok so far
b) both implement a fast reset option through bit 0, but with inverse logic!!!
the keyboard controller resets if bit 0 is lowered, the ioport 0x92 resets if bit 0 is raised.
c) all other bits have nothing in common at all.
see: http://www.brokenthorn.com/Resources/OSDev9.html
I have a proposed patch attached. Comments appreciated. The state of the A20 Gate is still
shared between ioport 0x92 and outport of the keyboard controller, but all other bits are ignored.
They might be used in the future to emulate e.g. hdd led activity or other usage of ioport 0x92.
I have tested the attached patch. memtest works again as expected. I think it crashed because it uses
ioport 0x92 directly to enable the a20 gate.
Peter
---
--- qemu-0.13.0/hw/pckbd.c 2010-10-15 22:56:09.000000000 +0200
+++ qemu-0.13.0-fix/hw/pckbd.c 2010-12-26 19:38:35.835114033 +0100
@@ -212,13 +212,16 @@
static void ioport92_write(void *opaque, uint32_t addr, uint32_t val)
{
KBDState *s = opaque;
-
- DPRINTF("kbd: write outport=0x%02x\n", val);
- s->outport = val;
- if (s->a20_out) {
- qemu_set_irq(*s->a20_out, (val>> 1)& 1);
+ if (val& 0x02) { // bit 1: enable/disable A20
+ if (s->a20_out) qemu_irq_raise(*s->a20_out);
+ s->outport |= KBD_OUT_A20;
+ }
+ else
+ {
+ if (s->a20_out) qemu_irq_lower(*s->a20_out);
+ s->outport&= ~KBD_OUT_A20;
}
- if (!(val& 1)) {
+ if ((val& 1)) { // bit 0: raised -> fast reset
qemu_system_reset_request();
}
}
@@ -226,11 +229,8 @@
static uint32_t ioport92_read(void *opaque, uint32_t addr)
{
KBDState *s = opaque;
- uint32_t ret;
-
- ret = s->outport;
- DPRINTF("kbd: read outport=0x%02x\n", ret);
- return ret;
+ return (s->outport& 0x02); // only bit 1 (KBD_OUT_A20) of port 0x92 is identical to s->outport
+ /* XXX: bit 0 is fast reset, bits 6-7 hdd activity */
}
static void kbd_write_command(void *opaque, uint32_t addr, uint32_t val)
@@ -340,7 +340,9 @@
kbd_queue(s, val, 1);
break;
case KBD_CCMD_WRITE_OUTPORT:
- ioport92_write(s, 0, val);
+ ioport92_write(s, 0, (ioport92_read(s,0)& 0xfc) // copy bits 2-7 of 0x92
+ | (val& 0x02) // bit 1 (enable a20)
+ | (~val& 0x01)); // bit 0 (fast reset) of port 0x92 has inverse logic
break;
case KBD_CCMD_WRITE_MOUSE:
ps2_write_mouse(s->mouse, val);
I just replied to the original thread. I think we should separate
0x92 and the keyboard controller port since they are quite different.
Fudging things just makes it tricky to understand.
what do you suggest? reverting the patch in total?
peter
Stefan
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