I've just pushed an update to the code here... On Mon, Apr 10, 2023 at 05:45:15PM +0200, Pascal Hambourg wrote: >On 10/04/2023 at 15:13, Steve McIntyre wrote: >> >> Overall comment: I'm not trying to make the heuristics 100% reliable >> here, as I don't think that's actually possible. Instead, I'm trying >> to tread the fine line of: >> >> * minimising false negatives - let's try to pick up on the most >> common cases where people are dual-booting with other systems and >> might not understand the issues here. That's 99%+ going to be >> people with Windows installed >> >> * minimising false positives - the issue that angered Cyril in >> particular, with an incomplete LVM setup triggering the "bios >> bootable OS" warning > >IMO it is more important to avoid false positives, because switching to a >BIOS installation on systems which are not BIOS-boot capable would create a >non bootable system. In case oft is easier to install GRUB for BIOS boot on >an running EFI system than the other way around.
No. The reason I added this check and warning in the first place is to avoid breaking existing (all-too-common) systems where Windows users have a BIOS-booting installation but their BIOS is set to boot both UEFI and BIOS. That's a stupid combination, but again all too common. :-( New users who are just trying to install Debian dual-boot are much less likely to be able to diagnose this kind of problem. >> > - Other BIOS boot loaders such as syslinux/extlinux do not need or use a >> > BIOS >> > boot partition. >> >> Also not a use case I'm particularly caring about, I'll be >> honest. They're also *really* not likely to work well without another >> filesystem in use, which I expect we'll detect anyway. > >Indeed other partitions are needed and will be detected, but they will not >increment $NUM_NOT_ESP if the disk is GPT and has no BIOS boot partition (so >$DISK_BIOS_BOOT=no), so it might cause a false negative. So why not just >treat MSDOS and GPT disk labels equally and treat BIOS boot partitions like >any other non-ESP ? It's a false negative that I really don't believe or care about very much, I'll be honest. This is getting to be an edge case on an edge case. >> > 1b) IIUC the patch fixes #1033913 because the disk selected for >> > installation >> > has received a new GPT disklabel without a BIOS boot partition, so further >> > checking is skipped. But IMO the root cause of #1033913 is that changes are >> > not committed to disk after setting the 'boot' and 'esp' flags to the newly >> > created ESP partition before stopping parted_server. > >I originally thought about fixing partman-auto-lvm but it appears that other >transient states can also trigger the "force UEFI installation" dialog during >partitioning, for example after setting up LVM in manual partitioning if >there is no ESP partition yet. As discussed in #debian-boot, a more general >fix might be to run the check only once because only existing partitions >before partitioning are relevant. Are there any use cases for which this >might cause a false negative ? So I've now modded the code to add a flag file - it'll only run the check and (maybe) raise the warning on the first entry into partman. Thanks for the suggection, this is clearly the correct answer. >> > 4) It appears that partman fails to detect the specially crafted partition >> > table on the installation media created with a debian image. Is it intended >> > or fortunately unintentional ? If partman could see the EFI partition on >> > the >> > installation media, the detection of BIOS-bootable systems would fail. >> >> That's not a worry for today... :-) > >Sure, but the issue can also happen if another removable media is present. >For instance the USB drive I use to provide missing firmware has an ESP >partition (and a regular partition table) thus can cause a false negative. Again, we're hitting edge cases. We can't know for sure what the user wants here, so we can't just ignore removable media (for example). -- Steve McIntyre, Cambridge, UK. st...@einval.com "Since phone messaging became popular, the young generation has lost the ability to read or write anything that is longer than one hundred and sixty characters." -- Ignatios Souvatzis
