On Fri 05 May 2017 at 13:53:00 (-0400), Stefan Monnier wrote: > >> Of course it all depends on what you mean by "booting from". AFAICT in > >> Leandro's situation, he's loading Grub from some other disk (probably > >> the main HDD or SSD), so he's already "not booting from the SD card" in > >> this sense. > > By "booting from" I mean everything which is needed to bring the OS up > > is located on the SD or CF card. > > AFAIK in his case, Grub itself is already on another device because the > BIOS can't boot directly from the SD card. So, he can't "boot from" his > SD card using your definition. > > > In essence, the card can be transferred to to another machine and will > > still boot. What you describe below I'd refer to as "booting into the > > OS" ; it cannoot be done without the assistance of software on the > > machine itself. I hope this is not an artificial distinction. > > I fully agree: I myself tried to setup a "rescue USB key" that could > boot everywhere, but that simply can't work on those machines whose > BIOS simply doesn't know how to boot from USB. > > > In principle this is a viable booting method but there are issues to be > > aware of. > > Oh, yes. > > > The kernel on the main HDD or SSD is unlikely to be the Tails > > kernel so a third device would be needed to hold such a kernel; > > You don't need a third device. You need to consciously/carefully save > your Tails kernel and initrd somewhere on the HDD/SSD. You can use > a separate "TAILS-BOOT" partition on that HDD/SSD for that, or you can > place them in "the normal partition" but under a special name like > "vmlinuz-tails" and "inird.img-tails".
I'm using a third device here for a different reason: what I'm booting is the netinst d-i, so the files on the hard drive will be blown away. I've booted From the pre-existing Grub2 on the hard drive, but Into the netinst.iso file on a FAT USB stick by loop-mounting it (Brian's terminology). That works fine until the d-i tries to read the "CD-ROM", but then it's simply a matter of pulling the FAT stick, inserting another one where netinst.iso has been copied to /dev/sdX itself (not to a FAT filesystem) and pressing Continue. > > The OP in the original thread actually booted in this way from the hard > > disk, but (as it fortuitously happened) kernel, initrd and OS on hard > > disk and SD card were identical. > > That must have been "beginner's luck", indeed. Actually, I think it was more because they used a sole Debian DVD for installing both the hard drive's system and the one on the SD. The OP in the original thread is probably one of the most experienced d-i installers on this list. Cheers, David.
