On Tue, 12 Aug 2014 19:29:02 +0200 Jeroen Hofstee <jer...@myspectrum.nl> wrote:
> Hello Stephan, > > On 11-08-14 20:55, Stephen Warren wrote: > > <snip> > > >>> No, Linux distros need to be able to install a single bootloader > >>> configuration file to tell the bootloader how to boot. > >> > >> Don't understand this, I though extlinux is yet another > >> chainloaded bootloader? I doubt there is "the bootloader". > >> I don't understand why it needs a single bootloader. It gets > >> in handy if the last bootloader is known, but I don't even see > >> why that is required. > > > > This is obviously where the disconnect is... > > > > extlinux is (IIRC) a bootloader yes. However, this patch isn't > > about extlinux, but extlinux.conf. > > > > haha, right that is a funny misunderstanding. Yes, extlinux is > indeed a bootloader and I was in the impression you actively > searched for it to chainload it. And to make extlinux a requirement > for distro support... And as I tried to explain I am not that fond of > such an approach in general, and that had nothing to do, as Tom > suggested, with booting FreeBSD, it is just the image I encountered > searching for it in various places. It remains a badly named file > though (for U-boot), but well so be it, I guess. u-boot in the pxe code has an implementation that parses the syslinux config file. though there really is nothing that says its a linux only thing, admittedly I'm a bit naive as to how things like freebsd boot but i assume you can load a kernel and pass some boot arguments just the same. We are looking for a extlinux.conf file as that's what extlinux looks for and we are mimicking the functionality. > > extlinux.conf is a text file format the defines a menu of bootable > > OSs. It's a (de-facto I suppose) standard that's implemented by > > extlinux (if indeed that is a piece of SW:-) and also U-Boot and > > barebox and likely other bootloaders too. > > > > So, when U-Boot locates extlinux.conf on disk and processes it, > > it's parsing a configuration file/menu, not chain-loading/executing > > another bootloader. > > > > I see, so shouldn't we document then who is in charge of its format > at least, before we start making a U-boot/distro specific version of > it? We are using the same format as is used by the syslinux project. we support a couple of optional items to specify the dtb, fdt and fdtdir, fdt is a location to a devicetree blob and fdtdir is a directory where you can find devicetree blobs. > <snip example file> > > > > That would require all Linux distros to have specific support to > > install boot.scr, which is a bootloader-specific format script > > file. Systems that boot using e.g. Barebox or other bootloaders > > presumably can't process boot.scr. However, if all bootloaders end > > up supporting extlinux.conf, the distro won't care what bootloader > > is on the HW. > > We will see if this works, I am bit skeptical, but it is at least a > whole lot > better then polling all possible options, where I took the patch for. > (Well not all yet, but the start to do so). Even with checking the different places that we can find the config file. There is no noise, u-boot doesn't print out when there is no files found only when it find them. The time to check for the existence of the file is very quick. Dennis _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
