Hi Pete, On Wed, Aug 07, 2019 at 03:24:10PM +0100, Pete Batard wrote: > > > +Below are steps you can follow to install Debian 10 onto an SD card: > > > +* Partition the media as MBR and create a ~300 MB partition on it with > > > MBR type `0x0e`. > > > + __Note:__ Make sure that the partition scheme is MBR (not GPT) and the > > > type `0x0e` (not > > > + `0xef` for instance), as the ondie Broadcom bootloader supports > > > neither the GPT scheme nor > > > > ondie -> on-die (or on-SoC may be even more clear to civilians). > > I think I'll use "on-CPU" then, as this should be even more explicit.
Works for me. > > > + the ESP MBR type. > > > +* Set the partition as active/bootable. This is needed as the Debian > > > partition manager can > > > + not detect it as ESP otherwise, which we need for GRUB installation. > > > If using `fdisk` on > > > + Linux, you can use the `a` command to set a partition as active. On > > > Windows, you can use > > > + `DISKPART` and then type `active` after selecting the relevant disk > > > and partition. > > > +* Format the partition as FAT. Here again you should make sure that you > > > use FAT rather than > > > + FAT32 else the Debian partition manager will not detect the partition > > > as ESP. If you > > > + are using Windows `DISKPART` then `format fs=fat quick` should do it. > > > On Linux, `mkfs.vfat` > > > + with the default options should do the same as long as the partition > > > isn't too large. > > > > It would be preferable if we could have an actual number here - the > > 12-bit, 16-bit and 32-bit fat size switchover points are known. I > > assume it is the 32-bit breakpoint (2 or 4Gb?) we want to avoid? > > The switchover point actually depends of the utility, since there is overlap > between 12, 16 and 32. But that's not actually a problem with diskpart on > Windows as 'fs=fat' does force FAT16 so you'll get an error if the partition > is too large and can only accommodate FAT32 (which should usually occur past > the 2 GB point). > > In other words, the only potential issue here is with Linux' mkfs.vfat. But > there too we can add a switch (-F 16) to force FAT16, so I'll alter the > documentation to have that, plus a note that mentions that the partition > should be under 2 GB. Sure, this is fine. > I'll also take this opportunity to stress out that the only reason we are > trying to force FAT16 here is because the Debian installer's partition > manager is very temperamental with regards to its detection of an ESP that > doesn't have either the relevant GUID for GPT or type 0xef for MBR, none of > which can be used on a Pi. There are actually cases where I have seen that > utility also detect a FAT32 MBR partition without type 0xef as an ESP. Yeah, well. This is pretty much stacking ice cubes next to a furnace, trying to create an ABI where there is none. Which is fine, because we do need to provide documentation for non-experts - but this is also why it needs to be precise, so we don't mislead experts. > However, I have found out that, in most cases, the presence of FAT32 vs > FAT16 acts as a switch to demote the partition from ESP, which is the reason > why the notes promote the use of FAT16 over FAT32. But as mentioned in the > additional notes however, it's still relatively easy to fix the ESP issue if > you use FAT32 and/or if the Debian partition manager fails to detect it as > ESP. Sure. May be worth adding a forward-pointer to the additional notes from here then? > Now, one can only wish that Broadcom had anticipated UEFI usage for their > hardcoded boot loader, as they'd only needed to have added 0xef, alongside > the other FAT based MBR partition types they recognize for this whole > annoyance to be avoided... In my most optimistic hours, I sometimes dare to hope that the EBBR explicitly stating these requirements will at some point in the future start to make a difference. > I'll send a v3 when I get a chance. Thanks! Regards. Leif -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#45009): https://edk2.groups.io/g/devel/message/45009 Mute This Topic: https://groups.io/mt/32599164/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
