On 08/11/2014 11:51 AM, Jeroen Hofstee wrote:
Hello Stephan
On 11-08-14 18:53, Stephen Warren wrote:
On 08/10/2014 10:53 AM, Jeroen Hofstee wrote:
Hello Stephan,
On 10-08-14 05:11, Stephen Warren wrote:
The entire point of this series is to prevent distros from having to install bootloader-specific boot configuration files.
I fail to see why this is something to pursue. Since the distro knows the boot path, why should u-boot be polling all possible options?
This patch series allows U-Boot to find the OS and boot it. U-Boot is searching for some kind of boot configuration file.
This part of the process is the same as the BIOS searching all known possible boot devices for a partition marked bootable, and with a valid MBR. Or, it's the same as UEFI searching all possible boot devices for whatever config file or boot binary is mandated by UEFI.
Not in my mind, I am not against scanning the possible boot devices, on the contrary, I am trying to add booting the userland from usb instead of mmc for the rpi_b.
The following will tell U-Boot to only search USB for extlinux.conf.
setenv boot_targets usb
(you can put this into /uEnv.txt on the SD card if you want to avoid editing U-Boot source code to make this change; there's no persistent environment storage on the Pi, at least at the moment)
The part I dislike is where it starts searching for specific files. The equivalent would be your BIOS actively searching for GRUB, LILO, Windows Boot manager etc. etc. and as a fallback try the MBR.
...
Once U-Boot locates extlinux.conf or boot.scr, that file encodes what files (kernel, DTB, initrd)
This is the part I get for free now with it, I don't really like it, since if we take this road it ends up looking for e.g. grub.conf, ubldr.conf, vxworks.conf etc etc.
No, Linux distros need to be able to install a single bootloader configuration file to tell the bootloader how to boot. I definitely don't want to add support for a ton of other bootloader configuration file formats. There needs to be a single standard that distros know they can rely on.
Also in this case the downstream provides information back, albeit tiny, it does indicate if it is bootable and a label to explain what is bootable.
I don't understand what that means.