qemu: use "ide" as device name for implicit SATA controller on Q35

This resolves https://bugzilla.redhat.com/show_bug.cgi?id=1008903

The Q35 machinetype has an implicit SATA controller at 00:1F.2 which
isn't given the "expected" id of ahci0 by qemu when it's created. The
original suggested solution to this problem was to not specify any
controller for the disks that use the default controller and just
specify "unit=n" instead; qemu should then use the first IDE or SATA
controller for the disk.

Unfortunately, this "solution" is ignorant of the fact that in the
case of SATA disks, the "unit" attribute in the disk XML is actually
*not* being used for the unit, but is instead used to specify the
"bus" number; each SATA controller has 6 buses, and each bus only
allows a single unit. This makes it nonsensical to specify unit='n'
where n is anything other than 0. It also means that the only way to
connect more than a single device to the implicit SATA controller is
to explicitly give the bus names, which happen to be "ide.$n", where
$n can be replaced by the disk's "unit" number.

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 4628dac73e3f3cc6e963ba4643273476b57976dc..e6239c993cd6c084a5ff13f9815f8635a33e8e98 100644 (file)
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -4383,18 +4383,15 @@ qemuBuildDriveDevStr(virDomainDefPtr def,
         if (qemuDomainMachineIsQ35(def) &&
             disk->info.addr.drive.controller == 0) {
             /* Q35 machines have an implicit ahci (sata) controller at
-             * 00:1F.2 which has no "id" associated with it. For this
-             * reason, we can't refer to it as "ahci0". Instead, we
-             * don't give an id, which qemu interprets as "use the
-             * first ahci controller". We then need to specify the
-             * unit with "unit=%d" rather than adding it onto the bus
-             * arg.
+             * 00:1F.2 which for some reason is hardcoded with the id
+             * "ide" instead of the seemingly more reasonable "ahci0"
+             * or "sata0".
              */
-            virBufferAsprintf(&opt, ",unit=%d", disk->info.addr.drive.unit);
+            virBufferAsprintf(&opt, ",bus=ide.%d", disk->info.addr.drive.unit);
         } else {
             /* All other ahci controllers have been created by
-             * libvirt, so they *do* have an id, and we can identify
-             * them that way.
+             * libvirt, and we gave them the id "ahci${n}" where ${n}
+             * is the controller number. So we identify them that way.
              */
             virBufferAsprintf(&opt, ",bus=ahci%d.%d",
                               disk->info.addr.drive.controller,

diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pcihole64-q35.args b/tests/qemuxml2argvdata/qemuxml2argv-pcihole64-q35.args
index e10ccb197570f967c233ded7fa085e9fc2a4ad9b..175c0dcf00c6d585cc13b8ef6aa70ab23e586f3c 100644 (file)
--- a/tests/qemuxml2argvdata/qemuxml2argv-pcihole64-q35.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-pcihole64-q35.args
@@ -5,5 +5,5 @@ LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
 -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x2 \
 -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x1 \
 -drive file=/dev/HostVG/QEMUGuest1,if=none,id=drive-sata0-0-0 \
--device ide-drive,unit=0,drive=drive-sata0-0-0,id=sata0-0-0 \
+-device ide-drive,bus=ide.0,drive=drive-sata0-0-0,id=sata0-0-0 \
 -vga qxl -global qxl.ram_size=67108864 -global qxl.vram_size=18874368

diff --git a/tests/qemuxml2argvdata/qemuxml2argv-q35.args b/tests/qemuxml2argvdata/qemuxml2argv-q35.args
index 4461eba1b84624b0aea599e82c82365d1dee2fd0..6bd5f4c0c2aca70e6ba0f1e27e7d85028fda6331 100644 (file)
--- a/tests/qemuxml2argvdata/qemuxml2argv-q35.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-q35.args
@@ -4,5 +4,5 @@ LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
 -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x2 \
 -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x1 \
 -drive file=/dev/HostVG/QEMUGuest1,if=none,id=drive-sata0-0-0 \
--device ide-drive,unit=0,drive=drive-sata0-0-0,id=sata0-0-0 \
+-device ide-drive,bus=ide.0,drive=drive-sata0-0-0,id=sata0-0-0 \
 -vga qxl -global qxl.ram_size=67108864 -global qxl.vram_size=18874368