Bug 707130

piix4_pm_initfn() expects the configured serial devices in serial_hds[].  Default serial device and devices created with -serial are there, but not the ones created with -device isa-serial.

Same issue with parallel_hds[], but isa-parallel devices are not supported in RHEL-6.

I believe the bug exists upstream as well.

Yes, it does.

Can be produced with qemu-kvm-0.12.1.2-2.163.el6.x86_64,marked qa_ack+

1.boot guest with -chardev tty,id=serial0,path=/dev/ttyS0 -device isa-serial,chardev=serial0

In guest
#udevadm info --query path --name /dev/ttyS0/
/devices/platform/serial8250/tty/ttyS0

2.boot guest with -serial /dev/ttyS0

In guest
udevadm info --query path --name /dev/ttyS0/
/devices/pnp0/00:06/tty/ttyS0

Reproduced on qemu-kvm-0.12.1.2-2.172.el6 and verified pass on qemu-kvm-0.12.1.2-2.177.el6.
Steps:
1. Boot guest A with
-chardev tty,id=serial0,path=/dev/ttyS0 -device isa-serial,chardev=serial0
Inside guest:
#udevadm info --query path --name /dev/ttyS0
#!! --attribute-walk | grep looking

2. Boot guest B with
-serial /dev/ttyS0
Inside guest:
#udevadm info --query path --name /dev/ttyS0
#!! --attribute-walk | grep looking

Results:
After fixed, the output of step 1 and step 2 are the same as following:
[root@dhcp-66-82-166 ~]# udevadm info --query path --name /dev/ttyS0
/devices/pnp0/00:06/tty/ttyS0
[root@dhcp-66-82-166 ~]# !! --attribute-walk | grep looking
udevadm info --query path --name /dev/ttyS0 --attribute-walk | grep looking
looking at device '/devices/pnp0/00:06/tty/ttyS0':
looking at parent device '/devices/pnp0/00:06':
looking at parent device '/devices/pnp0':

So, this bug is fixed.

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
When KVM guests were configured with the "-serial" option or the "-device isa-serial" option, serial devices created were displayed incorrectly by the system and were not visible by Windows guests. This issue arose because such devices were described incorrectly in the Advanced Configuration and Power Interface (ACPI) Differentiated System Description Table (DSDT). To fix this issue, the code has been modified to report such serial devices in the PCI IDE ISA Xcelerator 4 (PIIX4) configuration space. The system now shows these serial devices correctly and such devices are now registered by ACPI DSDT so Windows systems can now see these devices properly.

Fixed and cleaned up the description; the bug only occurs with "-serial", not
"-device isa-serial".  I omitted the expansion of ACPI, and avoided mentioning
PIIX4 which is just an implementation detail of current versions of QEMU.  In
general, if somebody really cares about how the fix works, they should know at
least what ACPI is, even though perhaps not that the fix involves the DSDT.

    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-When KVM guests were configured with the "-serial" option or the "-device isa-serial" option, serial devices created were displayed incorrectly by the system and were not visible by Windows guests. This issue arose because such devices were described incorrectly in the Advanced Configuration and Power Interface (ACPI) Differentiated System Description Table (DSDT). To fix this issue, the code has been modified to report such serial devices in the PCI IDE ISA Xcelerator 4 (PIIX4) configuration space. The system now shows these serial devices correctly and such devices are now registered by ACPI DSDT so Windows systems can now see these devices properly.+When KVM guests were launched with the "-device isa-serial" option instead of the "-serial" option (as libvirt does in Red Hat Enterprise Linux version 6), serial devices created were not visible by Windows guests. This issue arose because QEMU did not expose these devices in the guest's ACPI tables.  With the fix, the ACPI Differentiated System Description Table (DSDT) will properly sense the presence of serial devices and Windows guests will see them properly.

    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-When KVM guests were launched with the "-device isa-serial" option instead of the "-serial" option (as libvirt does in Red Hat Enterprise Linux version 6), serial devices created were not visible by Windows guests. This issue arose because QEMU did not expose these devices in the guest's ACPI tables.  With the fix, the ACPI Differentiated System Description Table (DSDT) will properly sense the presence of serial devices and Windows guests will see them properly.+When KVM guests were launched with the "-device isa-serial" option instead of the "-serial" option, serial devices created were not visible by Windows guests. This issue arose because QEMU did not expose these devices in guests' ACPI tables.  With this fix, the guest's ACPI Differentiated System Description Table (DSDT) now properly senses the presence of serial devices and Windows guests can now see them properly.

I've done several style corrections and reflected the description to the related advisory.

    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-When KVM guests were launched with the "-device isa-serial" option instead of the "-serial" option, serial devices created were not visible by Windows guests. This issue arose because QEMU did not expose these devices in guests' ACPI tables.  With this fix, the guest's ACPI Differentiated System Description Table (DSDT) now properly senses the presence of serial devices and Windows guests can now see them properly.+When KVM guests were launched with the "-device isa-serial" option instead of the "-serial" option, serial devices created were not visible by Windows guests. This issue arose because QEMU did not expose these devices in the guests' ACPI tables.  With this fix, the guest's ACPI Differentiated System Description Table (DSDT) now properly senses the presence of serial devices and Windows guests can now see them properly.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2011-1531.html