From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Mon, 11 Aug 2014 12:04:28 -0600 Subject: [U-Boot] [PATCH 1/3] config: introduce a generic $bootcmd In-Reply-To: <53E90294.7060604@myspectrum.nl> References: <1406759836-556-1-git-send-email-swarren@wwwdotorg.org> <53E25145.2090706@wwwdotorg.org> <53E4F400.6060508@wwwdotorg.org> <53E63816.60703@redhat.com> <53E6A3FE.6080807@myspectrum.nl> <53E6E2D0.7090303@wwwdotorg.org> <53E7A3A2.80707@myspectrum.nl> <53E8F50A.1060606@wwwdotorg.org> <53E90294.7060604@myspectrum.nl> Message-ID: <53E905AC.9050903@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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.