[Libguestfs] [v2v PATCH v2] convert_linux: translate the first CD-ROM's references in boot conf files

If the only CD-ROM in "s_removables" is on an IDE controller, and the guest kernel represents it with a /dev/hdX device node, then convert references to this device node, in the boot config files, to /dev/cdrom. On the destination (after conversion), /dev/cdrom will point to whataver node we converted the CD-ROM to, masking a potential i440fx -> q35 (IDE -> SATA) board change. If the only CD-ROM is not on an IDE controller, or the guest is modern enough to represent the IDE CD-ROM as /dev/sr0, then perform no translation. Namely, /dev/sr0 survives a potential i440fx -> q35 (IDE -> SATA) board change intact. When multiple CD-ROMs exist, emit a warning, and attempt the conversion on the first CD-ROM, as a guess. This may be inexact, but we can't do better, because: - SATA, SCSI, and (on modern guests) IDE CD-ROMs are lumped together in the /dev/sr* namespace, on the source side, and "s_removable_slot" is useless for telling them apart, as we don't know the exact controller topology (and OS enumeration order); - after conversion: some OSes don't create /dev/cdrom* symlinks to all CD-ROMs, and even if multiple such symlinks are created, their order is basically random. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1637857 Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; --- Notes: v2: - Use List.length >= 2 rather than matching with three cons operations. [Rich] - At the same time, eliminate wrong precedence between "->" in a match, and ";". [Rich] - Match the first element of the cdrom list, and the contents of that element, in a single "match" expression. [Rich] - Not tested, due to the issue I described in <8b3ce08b-ea47-dc1c-f441-c8b91708bd6f(a)redhat.com&gt; (cannot provide a mailing list URL because the archive seems to have stopped refreshing itself?) convert/convert_linux.ml | 19 +++++++++++++++++++ tests/test-v2v-cdrom.expected | 2 +- tests/test-v2v-cdrom.xml.in | 4 +++- tests/test-v2v-i-ova.xml | 2 +- 4 files changed, 24 insertions(+), 3 deletions(-) diff --git a/convert/convert_linux.ml b/convert/convert_linux.ml index 8dc648169dcb..d49ecec03aeb 100644 --- a/convert/convert_linux.ml +++ b/convert/convert_linux.ml @@ -1020,6 +1020,25 @@ let convert (g : G.guestfs) source inspect keep_serial_console _ = "xvd" ^ drive_name i, block_prefix_after_conversion ^ drive_name i ) source.s_disks in + (* Check the first CD-ROM. If its controller is IDE, and the OS is RHEL<=5, + * then translate the CD-ROM from "/dev/hd[SLOT]" to "/dev/cdrom". See + * RHBZ#1637857 for details. + *) + let cdroms = List.filter + (fun removable -> removable.s_removable_type = CDROM) + source.s_removables in + if List.length cdroms >= 2 then + warning (f_"multiple CD-ROMs found; translation of CD-ROM references \ + may be inexact"); + let map = map @ + (match cdroms with + | { s_removable_controller = Some Source_IDE; + s_removable_slot = Some slot } :: _ + when family = `RHEL_family && inspect.i_major_version <= 5 -> + [("hd" ^ drive_name slot, "cdrom")] + | _ -> [] + ) in + if verbose () then ( eprintf "block device map:\n"; List.iter ( diff --git a/tests/test-v2v-cdrom.expected b/tests/test-v2v-cdrom.expected index 34d2bf5961b0..17bd152d8e64 100644 --- a/tests/test-v2v-cdrom.expected +++ b/tests/test-v2v-cdrom.expected @@ -4,5 +4,5 @@ </disk> <disk device='cdrom' type='file'> <driver name='qemu' type='raw'/> - <target dev='hdc' bus='ide'/> + <target dev='sdc' bus='sata'/> </disk> diff --git a/tests/test-v2v-cdrom.xml.in b/tests/test-v2v-cdrom.xml.in index 6bad5eab1cd4..a6e1e3f514d5 100644 --- a/tests/test-v2v-cdrom.xml.in +++ b/tests/test-v2v-cdrom.xml.in @@ -35,7 +35,9 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file=&#39;@abs_top_builddir(a)/test-data/phony-guests/blank-disk.img&#39;/&gt; - <!-- virt-v2v should preserve the device name and bus --> + <!-- virt-v2v should change the bus to sata, due to Windows 7 + triggering a machine type change from i440fx to q35. Beyond that, + virt-v2v should preserve the on-bus index. --> <target dev='hdc' bus='ide'/> </disk> </devices> diff --git a/tests/test-v2v-i-ova.xml b/tests/test-v2v-i-ova.xml index d7383905fdc0..9f3c1974243f 100644 --- a/tests/test-v2v-i-ova.xml +++ b/tests/test-v2v-i-ova.xml @@ -28,7 +28,7 @@ </disk> <disk device='cdrom' type='file'> <driver name='qemu' type='raw'/> - <target dev='hda' bus='ide'/> + <target dev='sda' bus='sata'/> </disk> <disk device='floppy' type='file'> <driver name='qemu' type='raw'/> -- 2.19.1.3.g30247aa5d201