On Mon 14 May 2018 at 09:14:23 (-0400), Stefan Monnier wrote: > > That said, there are other statements that are odd: > > Not sure what you find odd about them: > > > "I really can’t recommend strongly enough that you do not attempt > > to mix UEFI-native and BIOS-compatible booting of > > permanently-installed operating systems on the same computer, and > > especially not on the same disk. It is a terrible terrible idea > > and will cause you heartache and pain. If you decide to do it, > > don’t come crying to me." (under "UEFI booting: background"). > > Here he's just saying that there's a good chance you'll encounter > difficulties if you try that, and indeed in my experience the behavior > of such a config will depend on undocumented details.
Yes, documentation of firmware is almost unknown in my experience (since probably 30 years ago). That's why I took the least invasive method that I could. Using a UEFI/UEFI approach means that you have to explore the manufacturer's undocumented implementation of UEFI. Plenty of horror stories there, including Pascal's. > > "Disk formats (MBR vs. GPT) > > > > Here’s another very important consideration: > > > > If you want to do a ‘BIOS compatibility’ type installation, you > > probably want to install to an MBR formatted disk. If you want to > > do a UEFI native installation, you probably want to install to a > > GPT formatted disk." > > Same here (basically for the same reason: the behavior of the firmware > and OS when faced with a disk that has both a GPT and an MBR partitions > is largely unspecified and will vary depending on your system). Eh? I've yet to see a GPT disk that didn't have a protective MBR. I thought that's the reason why GPT starts at block 1 and not block 0: an MBR was designed into GPT from the start (no pun intended). > > I can't reconcile that with the system here, a Windows 8→10 UEFI laptop > > and GPT disk running linux in BIOS compatibility mode (here called > > Legacy mode by Lenovo) booting from an MBR on an ATA disk: > > It's easy to reconcile: he doesn't say your setup is impossible or can't > work, he just recommends not to do that because you may encounter > unexpected difficulties. E.g. in theory an upgrade to your firmware or > to one of your OSes could break it, tho in practice you're probably OK > at least until you move that setup to another machine with > a different firmware. Not sure what you mean here. It's a laptop: nowt's going nowhere. But in a page as long as this one is, I think the author is rather dismissive of using Legacy mode at all. Perhaps the clue is here: "Don’t do UEFI-native installs to MBR-formatted disks, or BIOS compatibility installs to GPT-formatted disks (an exception to the latter is if your disk is, IIRC, 2.2+TB in size, because the MBR format can’t handle disks that big – if you want to do a BIOS compatibility install to a disk that big, you’re kinda stuck with the BIOS+GPT combination, which works but is a bit wonky and involves the infamous ‘BIOS Boot partition’ you may recall from Fedora 17). I haven't been able to find anything infamous about the BIOS Boot partition but it sounds as if the author had a bad experience at sometime in the past which has affected their ability to view the topic objectively. Cheers, David.