On 21/01/2019 18:21, Bruce Dubbs via lfs-dev wrote: > On 01/21/2019 09:05 AM, Pierre Labastie via lfs-dev wrote: >> On 21/01/2019 11:09, Xi Ruoyao via lfs-dev wrote: >>> On 2019-01-21 10:44 +0100, Pierre Labastie via lfs-dev wrote: >>>> Hi, >>>> >>>> My machine has an UEFI BIOS, so that I rarely run grub-install. But >>>> yesterday, >>>> I built a new qemu VM, with a non-UEFI (virtual) BIOS. When running >>>> grub-install, it failed with a message (sorry, I haven't saved it) telling >>>> that it could not find /usr/lib/grub/x86_64-efi. Running "grub-install >>>> --help" >>>> returned: >>>> --------- >>>> [...] >>>> --target TARGET install GRUB for TARGET platform [default=x86_64-efi] >>>> [...] >>>> --------- >>>> so I had to run "grub-install --target i386-pc /dev/sda". But now that I >>>> have >>>> done that, "grub-install --help" returns: >>>> --------- >>>> [...] >>>> --target TARGET install GRUB for TARGET platform [default=i386-pc] >>>> [...] >>>> --------- >>>> >>>> So the default seems to be what is already installed. Checking the source >>>> for >>>> grub-install confirms that. I must have taken a virtual disk used for a >>>> former >>>> VM with UEFI BIOS. >>> >>> No. Grub 2.02 is detecting the target dynamically at runtime by checking if >>> /sys/firmware/efi is empty. At first time your system was booted via UEFI >>> so >>> this is not empty. But at the second time your system was booted via Legacy >>> BIOS so this is empty. >> >> You are right about the process, but what amazes me is that the first boot >> was >> not particularly EFI. I had a DOS partitioning (not GPT), and no /boot/EFI >> dir, and yet it must have found something in /sys/firmware/efi since it >> proposed x86_64 as the default (I do have the EFI switches on in the kernel). >> Well, looks like it will be hard to reproduce. >> >>> >>>> Should we add this switch (--target i386-pc) to the grub-install command in >>>> the book? >>> >>> If the host is booted via UEFI we'll need that to install a non-UEFI Grub. >>> But I think it's dangerous (may break the booting process of the host). We >>> should explain this option more seriously (maybe in a "NOTE" or even >>> "CAUTION"). >>> >> >> Yes, that may break machines with only UEFI boot. I think the command should >> be written without "--target", as it is now, but a note should be added to >> explain that the --target option may be used if the wrong if the application >> default is wrong > > Agree. Please do that when you get a chance.
I've added a note at r11503. Not sure I have the wording right. Pierre -- http://lists.linuxfromscratch.org/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
