Hi Tom, On Thu, 19 Aug 2021 at 07:59, Tom Rini <tr...@konsulko.com> wrote: > > On Wed, Aug 18, 2021 at 09:45:33PM -0600, Simon Glass wrote: > > > Bootmethod and bootflow provide a built-in way for U-Boot to automatically > > boot > > an Operating System without custom scripting and other customisation: > > > > - bootmethod - a method to scan a device to find bootflows (owned by > > U-Boot) > > - bootflow - a description of how to boot (owned by the distro) > > > > This series provides an initial implementation of these, enable to scan > > for bootflows from MMC and Ethernet. The only bootflow supported is > > distro boot, i.e. an extlinux.conf file included on a filesystem or > > tftp server. It works similiarly to the existing script-based approach, > > but is native to U-Boot. > > > > With this we can boot on a Raspberry Pi 3 with just one command: > > > > bootflow scan -lb > > > > which means to scan, listing (-l) each bootflow and trying to boot each > > one (-b). The final patch shows this. > > > > It is intended that this approach be expanded to support mechanisms other > > than distro boot, including EFI-related ones. With a standard way to > > identify boot devices, these features become easier. It also should > > support U-Boot scripts, for backwards compatibility only. > > > > The first patch of this series moves boot-related code out of common/ and > > into a new boot/ directory. This helps to collect these related files > > in one place, as common/ is quite large. > > > > Like sysboot, this feature makes use of the existing PXE implementation. > > Much of this series consists of cleaning up that code and refactoring it > > into something closer to a module that can be called, teasing apart its > > reliance on the command-line interpreter to access filesystems and the > > like. Also it now uses function arguments and its own context struct > > internally rather than environment variables, which is very hard to > > follow. No core functional change is included in the included PXE patches. > > > > For documentation, see the 'doc' patch. > > > > There is quite a long list of future work included in the documentation. > > One question is the choice of naming. Since this is a bootloader, should > > we just call this a 'method' and a 'flow' ? The 'boot' prefix is already > > shared by other commands like bootm, booti, etc. > > > > The design is described here: > > > > https://drive.google.com/file/d/1ggW0KJpUOR__vBkj3l61L2dav4ZkNC12/view?usp=sharing > > > > The series is available at u-boot-dm/bmea-working > > My question / concern is this. Would the next step here be to > implement the generic UEFI boot path? Today, I can write Fedora 34 for > AArch64 to a USB stick, boot U-Boot off of uSD card and the installer > automatically boots. I'm sure I could do the same with the BSDs. > Reading the documentation left me with the impression that every OSV > would be expected to write something, so that their installer / OS boot. > But there's already standards for that, which they do, and we should be > implementing (and do, via the current distro_boot) or making easier to > enable. Thanks!
Here you are talking about scanning for a bootflow. It is not actually OS-specific. If it were, there would be no point to this :-) If you look in the distro scripts you will see 'scan_dev_for_efi' (and also scan_dev_for_scrips). At least the first needs to be implemented a bit like the distro boot is at present. So far I have only implemented scan_dev_for_extlinux (plus pxe) as it is enough to show the concept. Adding EFI it's likely to be about the same amount of code as distro.c at present, perhaps a little less since we don't have the network case. It is used by Fedora 34, I believe, so is easy enough for me to do. But I wanted to get something out as the concept is visible in this series. Regards, Simon
