On Fri, Jun 28, 2013 at 01:11:40PM +0200, Michal Privoznik wrote:
Because of some crazy backward compatibility, console device is in
some cases just an alias to a serial device. This means, in the process
of generating XML description of a domain, all the interesting info is
taken from corresponding serial device, if that's the case. Including
the device alias. That means, we produce:
<console type='pty' tty='/dev/pts/20'>
...
<alias name='serial0'/>
</console>
(notice the assigned alias)
Maybe this is okay, maybe its wrong either. Anyway, later, when libvirtd
restarts, and we parse the state XML file, we read the wrong alias back.
Hence, the internal representation is different to the state it was in
prior the libvirtd restart.
---
src/qemu/qemu_domain.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 8d79066..96d88ec 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -804,6 +804,34 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
dev->data.chr->source.data.nix.listen = true;
}
+ /* For some really crazy back compat in virDomainDefFormatInternal we must
+ * restore the original console alias. For hvm domains, we are formatting
+ * a dummy console device (based on a serial device which it refers to)
+ * instead of the original one. That means the device aliases in memory
+ * and in the formatted XML are not in sync. While in memory we still have
+ * 'consoleN', in the formatted XML we have 'serialN'. */
+ if (dev->type == VIR_DOMAIN_DEVICE_CHR &&
+ dev->data.chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_CONSOLE
&&
+ dev->data.chr->targetType == VIR_DOMAIN_CHR_CONSOLE_TARGET_TYPE_SERIAL
&&
+ STREQ(def->os.type, "hvm")) {
+ int id;
+ char *alias = dev->data.chr->info.alias;
+ const char *serial_alias = "serial";
+
+ if (alias && STRPREFIX(alias, serial_alias)) {
+ alias += strlen(serial_alias);
+
+ if (virStrToLong_i(alias, NULL, 10, &id) < 0)
+ goto cleanup;
+
+ VIR_FREE(dev->data.chr->info.alias);
+ if (virAsprintf(&dev->data.chr->info.alias, "console%d",
id) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+ }
+ }
+
ret = 0;
cleanup:
Ok, the situation we have is
- The VM is configured with a <serial> port
- The <serial> port config is copied to <console> for purposes of
back compatibility
- After starting the guest
QEMU has a device with id==serial0
while virDomainDefPtr has
def->seriales[0]->info == "serial0"
def->consoles[0]->info == "console0"
and the XML shown to the user, and saved to the state XML is
<serial type='pty'>
<source path='/dev/pts/7'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/7'>
<source path='/dev/pts/7'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
This inconsistency/inaccuracy in the virDomainDefPtr is bad
- After re-starting libvirtd, while the guest is runing
def->seriales[0]->info == "serial0"
def->consoles[0]->info == "serial0"
because it got this data from the state XML file and
the XML shown to the user remains:
<serial type='pty'>
<source path='/dev/pts/7'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/7'>
<source path='/dev/pts/7'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
So the inconsistency has been fixed at this point
IIUC, this patch is intended to change things so that after libvirtd is
restarted, we get:
def->seriales[0]->info == "serial0"
def->consoles[0]->info == "console0"
but this is fixing the wrong thing. There is only one physical device
emulated in the guest, which is a serial port with id==serial0, and
this is reflected correctly in the XML we generate. Only the internal
struct is different.
So what needs fixing is the code which populated def->consoles[0]->info
with "console0" instead of the correct "serial0" string at VM
startup.
Regards,
Daniel
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