Re: UEFI corner case - installer booted in UEFI mode, existing system in BIOS mode
On Sun, Sep 28, 2014 at 02:28:06AM +0100, Steve McIntyre wrote:
> I'm not 100% sure that partman-efi is the right package for the bug
> report, but it's as good as any. So, it's way past time to fix this
> particular bug. After a fair amount of playing with systems like this
> and discussing with folks, my proposed solution is:
>
> 1. Somewhere during initial partman setup (probably partman-efi?), we
> look to see if:
>
> (a) we're in UEFI mode (trivially true if we're in partman-efi); and
>
> (b) we have an existing set of partitions that are *not* set up
> for UEFI boot (can we use os-prober to get a list at this
> stage?) Look for an existing partition setup and maybe
> bootable flags, but no detectable EFI System Partition.
>
> 2. If the above is the case, warn the user:
>
> "Your computer's firmware has started the installer in UEFI mode
> but there are existing Operating Systems already installed:
>
> * OS 1
> * OS 2
> ...
>
> "These will not boot in UEFI mode. If you still wish to be able
> to boot one of these existing systems after installing Debian in
> UEFI mode, this will be difficult. Your best way forward is to
> reboot and restart the installer in 'BIOS compatibility
> mode'. You will need to reconfigure your computer's boot options
> to do this.
>
> "If you wish to install Debian in UEFI mode and don't care about
> keeping the ability to boot one of the existing systems,
> continue."
>
> <Go Back> <Continue>
>
> If the user wants to continue, we could even suggest blanking the
> partition table(s) and starting again with GPT, but I don't think
> we currently have a "blank partition table" option exposed within
> d-i?
>
> What do people think of this plan? What have I missed?
Isn't it better to run this test in partman-efi's isinstallable script?
Then if things are set up in the described way, grub-efi just won't be
installed, but the normal grub will, and the system will continue to
boot in BIOS fallback as before.
It might make sense to give a warning or error message in case the
described setup exists and an ESP partition is created in the
partitioner, but other than that...
--
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-- Barack Obama, speaking in Brussels, Belgium, 2014-03-26
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