On Sun, 20 Mar 2016 12:51:56 +0100 Pascal Hambourg <email@example.com> wrote: > Adam Wilson a écrit : > > > > There is a potential problem also where modern machines (with UEFI > > boot) fail to install off USB without UEFI, meaning that if you > > want a UEFI-free install, you have to use optical media. > > I have a rather old (~2007) UEFI motherboard which does the opposite : > its UEFI firmware lacks USB and AHCI drivers so it is impossible to > boot in UEFI mode from a USB device or from a SATA drive in AHCI mode. > > > This happened to me > > on an ASUS UX51vz with UEFI- with Debian 7 d-i, inserting an optical > > disc would provide the option to either boot the disk with UEFI or > > without it, > > Was this option displayed in the regular firmware boot menu or in a > different menu ? The boot order menu in the UEFI settings. > > while inserting a USB would only allow UEFI boot from the > > flash drive, and not legacy booting, even with Launch CSM enabled. > > Do you mean the the firmware boot menu only displayed one option (EFI > mode) for the USB device ? Yes. > Did you try to boot a non-EFI capable USB boot media, such as a Debian > live image or a Debian installation image with the EFI partition > deleted ? No. That did not occur to me; I assumed it would then refuse to boot at all. I shall try this out and get back to you. > > So while using Debian 7, I just had to use optical media to install > > Debian sans UEFI (which I always do- call it nostalgia, but I like > > the simplicity of MBR and four primary partitions rather than the > > unfamiliar layers of GPT/UEFI related cruft). > > Note that UEFI is not tied to GPT and vice versa. I happily use GPT on > legacy systems when I need many partitions and LVM is not an option. > Extended and logical partitions just suck. And I don't like / don't need either GPT, LVM, or logical volumes! Four primary partitions has always been enough for me. > > Booting off USB (forced > > to use UEFI) would simply result in a black screen after selecting > > "Install". > > I have seen this display problem with the EFI framebuffer driver in > Wheezy's kernel on some machines. Installing with a serial console > worked. How does one do that? > > Debian 8, however, seems to have solved this problem. > > Indeed, the kernel EFI framebuffer driver in Jessie's driver seems to > have been improved. I wouldn't know anything about that, but from my field experience UEFI works with far less hassle in Jessie as opposed to Wheezy. > > USB can still > > only be booted from UEFI, but newer d-i means that installation now > > proceeds as normal until the point at which UEFI yes/no > > (force/leave) selection is reached > > I don't remember seeing this option in Jessie's installer when booted > in EFI mode. How is it labeled exactly ? At what stage is it > proposed ? It isn't something I saw either until my first UEFI installation media boot- it may have been triggered by the fact that I was using 'Launch CSM' Legacy mode so that I wouldn't have to bother with GPT/UEFI and could use something resembling traditional BIOS and MBR. It is in between the tasksel stage and the GRUB installation stage. A prompt appeared telling me that I could either 'Force UEFI' for the operating system installation, and have Jessie configured to boot from UEFI, or not. It detected the fact that I had booted from UEFI but my system was capable of either booting method.
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