Bug#763127: UEFI corner case - installer booted in UEFI mode, existing system in BIOS mode
Package: partman-efi
Version: 47
Severity: important
Tags: d-i
Ad originally described in [1], but no bug was ever filed to
match. #695048 is related, I think. Time to file a bug about this to
help track work to fix it...
We have a machine with both UEFI and BIOS-mode boot available, with an
existing BIOS-mode Windows installation (e.g. Windows 7 in this case)
*but* the machine is set up to try and boot UEFI first and *then* fall
back to BIOS (for some reason).
The existing Windows installation boots via the fallback, and the user
has no reason to ever investigate this. However, d-i will happily boot
in UEFI mode. When we get to partitioning, there is no EFI System
Partition (ESP), as Windows isn't using one. We then get to either of
two potentially bad cases:
(a) the user shuffles partitions around and makes an ESP, installs
the system OK including grub-efi. They then have a machine that
will boot via UEFI to grub, but maybe will not be able to boot
Windows. I've not tested this directly yet, but I can see this
happening. To get to their existing Windows installation, the
user will have to switch boot mode in the firmware setup - bad.
(b) the user does not make an ESP, installs a system but grub-efi
fails to install properly for that reason. I'm seeing bug reports
that suggest this path does *not* necessarily give a clear error
to the user, maybe in some cases no error at all. They reboot
their newly-installed system and find it immediately goes into
Windows with no sign of their new Debian installation at all.
[1] https://lists.debian.org/debian-boot/2014/02/msg00080.html
-- System Information:
Debian Release: 7.6
APT prefers stable
APT policy: (500, 'stable'), (500, 'oldstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Reply to: