On 12/02/22 13:58, Richard W.M. Jones wrote:
On Fri, Dec 02, 2022 at 01:44:09PM +0100, Laszlo Ersek wrote:
> The "fallback" (or "default") boot behavior is described at great
length
> here:
>
>
https://blog.uncooperative.org/uefi/linux/shim/efi%20system%20partition/2...
>
> The gist of it applies to all UEFI OSes, including Windows. For the
> fallback boot behavior to work, the \EFI\BOOT\BOOTX64.efi boot loader on
> the EFI system partition must match the installed operating system. We've
> encountered a physical machine, during a virt-p2v conversion, where (a)
> \EFI\BOOT\BOOTX64.efi belongs to a previously installed, but now wiped,
> RHEL (hence shim+grub) deployment, and (b) the currently installed
> operating system is Windows.
>
> Virt-v2v never transfers the UEFI variables (including the UEFI boot
> options) of the source, therefore the converted VM always relies on the
> default boot behavior when it is first started up. In the above scenario,
> where \EFI\BOOT\BOOTX64.efi is actually "shim", the mismatch is triggered
> at first boot after conversion, and a broken grub shell is reached instead
> of the Windows boot loader.
>
> Detect this situation by investigating \EFI\BOOT\BOOTX64.efi on the EFI
> system partition of a Windows disk image. If the file is missing, or is
> not -- as expected -- a duplicate of \EFI\Microsoft\Boot\bootmgfw.efi,
> then copy the latter to the former.
>
> Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=2149629
> Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
> ---
>
> Notes:
> Tested with a freshly installed Win2019 guest whose
> \EFI\BOOT\BOOTX64.efi binary I manually corrupted.
>
> convert/convert_windows.ml | 25 ++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/convert/convert_windows.ml b/convert/convert_windows.ml
> index 34a5044dd338..57a7ff03398f 100644
> --- a/convert/convert_windows.ml
> +++ b/convert/convert_windows.ml
> @@ -836,17 +836,42 @@ let convert (g : G.guestfs) _ inspect _ static_ips =
> );
> with
> Not_found -> ()
> +
> + and fix_win_uefi_fallback esp_path uefi_arch =
> + (* [esp_path] is on NTFS, and therefore it is considered case-sensitive;
> + * refer to
> + * <
https://libguestfs.org/guestfs.3.html#guestfs_case_sensitive_path>.
> + * However, the EFI system partition mounted under [esp_path] is FAT32 per
> + * UEFI spec, and the Linux vfat driver in the libguestfs appliance treats
> + * pathnames case-insensitively. Therefore, we're free to use any case in
> + * the ESP-relative pathnames below.
It'd be nicer to keep the lines under 80 columns in length here for
ease of reading. I think these are exactly 80 columns?
Yes, the longest two lines have exactly 80 chars each. For years I've
used 79, but I kept finding preexistent code lines in various projects
that were 80 chars.
The command
git grep -E '^.{80}$' -- '*.ml*'
returns a good number of lines in v2v as well, and the command
git grep -E '^.{80,}$' -- '*.ml*'
even more.
> + *)
> + let bootmgfw = sprintf "%s/efi/microsoft/boot/bootmgfw.efi" esp_path
in
> + if g#is_file bootmgfw then
> + let bootdir = sprintf "%s/efi/boot" esp_path in
> + let fallback = sprintf "%s/boot%s.efi" bootdir uefi_arch in
> + if not (g#is_file fallback) || not (g#equal fallback bootmgfw) then (
I'm going to say that you don't need the parens around (g#is_file ...)
and (g#equal ...), but I'm actually not 100% certain about it.
Normally function application binds tightest. Anyway if true, it's a
matter of preference.
The parens are required:
# open Printf;;
# let f () = false;;
val f : unit -> bool = <fun>
# if not f () then printf "hello\n";;
Characters 3-6:
if not f () then printf "hello\n";;
^^^
Error: This function has type bool -> bool
It is applied to too many arguments; maybe you forgot a `;'.
# if not (f ()) then printf "hello\n";;
hello
- : unit = ()
> + info (f_"Fixing UEFI bootloader.");
> + g#rm_rf bootdir;
> + g#mkdir_p bootdir;
Is it safe to completely delete this directory or would it be better
to only delete the errant BOOTX64.efi file? I'm just wondering if
anything else important might be stored here.
Yes I think we *should* delete the \EFI\BOOT directory in this case.
We've determined that a Windows OS is installed on the disk, and I've
not seen any Windows version yet where \EFI\BOOT contained any other
file than BOOTX64.efi (or BOOTX32.efi), with the file being a copy of
bootmgfw.efi at that.
In the particular problem scenario
<
https://bugzilla.redhat.com/show_bug.cgi?id=2149629#c6>, replacing only
the BOOTX64.efi file (= shim) with a copy of bootmgfw.efi would produce
a \EFI\BOOT directory containing two files:
- BOOTX64.efi (= bootmgfw.efi)
- fbx64.efi (from the shim installation)
While that might not necessarily cause runtime issues, it's certainly
confusing for any human reader (does not look like pristine ESP contents
with Windows installed).
> + g#cp_a bootmgfw fallback
> + )
> in
>
> match inspect.i_firmware with
> | I_BIOS -> ()
> | I_UEFI esp_list ->
> let esp_temp_path = g#mkdtemp "/Windows/Temp/ESP_XXXXXX" in
> + let uefi_arch = get_uefi_arch_suffix inspect.i_arch in
>
> List.iter (
> fun dev_path ->
> g#mount dev_path esp_temp_path;
> fix_win_uefi_bcd esp_temp_path;
> + (match uefi_arch with
> + | Some uefi_arch -> fix_win_uefi_fallback esp_temp_path uefi_arch
> + | None -> ()
> + );
> g#umount esp_temp_path;
> ) esp_list;
Reviewed-by: Richard W.M. Jones <rjones(a)redhat.com>
If you can push this (optionally changed/fixed as you see fit) in the
next hour then I can put it into C9S, since I'm doing a build today
anyway.
Thanks, I'll push the series in a few minutes.
Laszlo
Rich.