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authorPaolo Bonzini <pbonzini@redhat.com>2013-11-04 14:30:47 +0100
committerMichael S. Tsirkin <mst@redhat.com>2013-11-04 15:39:41 +0200
commitdf39076850958b842ac9e414dc3ab2895f1877bf (patch)
tree0cd2a17c667731f1d0b9ef9427eb641771838f9d /gdbstub.c
parent818f86b88394b7b2b59d313e51043fe15a8004db (diff)
downloadqemu-arm-df39076850958b842ac9e414dc3ab2895f1877bf.tar.gz
vl: allow "cont" from panicked state
After reporting the GUEST_PANICKED monitor event, QEMU stops the VM. The reason for this is that events are edge-triggered, and can be lost if management dies at the wrong time. Stopping a panicked VM lets management know of a panic even if it has crashed; management can learn about the panic when it restarts and queries running QEMU processes. The downside is of course that the VM will be paused while management is not running, but that is acceptable if it only happens with explicit "-device pvpanic". Upon learning of a panic, management (if configured to do so) can pick a variety of behaviors: leave the VM paused, reset it, destroy it. In addition to all of these behaviors, it is possible to dump the VM core from the host. However, right now, the panicked state is irreversible, and can only be exited by resetting the machine. This means that any policy decision is entirely in the hands of the host. In particular there is no way to use the "reboot on panic" option together with pvpanic. This patch makes the panicked state reversible (and removes various workarounds that were there because of the state being irreversible). With this change, management has a wider set of possible policies: it can just log the crash and leave policy to the guest, it can leave the VM paused. In particular, the "log the crash and continue" is implemented simply by sending a "cont" as soon as management learns about the panic. Management could also implement the "irreversible paused state" itself. And again, all such actions can be coupled with dumping the VM core. Unfortunately we cannot change the behavior of 1.6.0. Thus, even if it uses "-device pvpanic", management should check for "cont" failures. If "cont" fails, management can then log that the VM remained paused and urge the administrator to update QEMU. Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'gdbstub.c')
-rw-r--r--gdbstub.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/gdbstub.c b/gdbstub.c
index 0e5a3f5bf9..e8ab0b2992 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -368,9 +368,6 @@ static inline void gdb_continue(GDBState *s)
#ifdef CONFIG_USER_ONLY
s->running_state = 1;
#else
- if (runstate_check(RUN_STATE_GUEST_PANICKED)) {
- runstate_set(RUN_STATE_DEBUG);
- }
if (!runstate_needs_reset()) {
vm_start();
}