On Tue, Oct 01, 2013 at 12:41:15PM +0200, Maxime Bizon wrote: > On Monday 30 Sep 2013 à 23:14:49 (-0400), Nicolas Pitre wrote: > > > > That "kind of hacky" ATAG thing was actually the only supported way to > > > boot a platform not so long ago :) > > > > Strictly speaking, this was never supported in mainline. I was referring to the non-approved atags many vendors arbitrarily added to their bootloaders and kernels. Ethernet mac addresses, etc. It's not proper to go cluttering the kernel with every hair-brained, one-off tag a board vendor came up with to ship a product. > > The ultimate idea with the impedance matcher was to augment existing > > bootloaders with sort of a semi second stage bootloader that would be > > separate from zImage and installed permanently, and then only the zImage > > itself would be updateable. This way you'd get a DT capable environment > > without replacing the actual bootloader. > > That's true if you have access to the bootloader in some way (serial, > flash env). > > But for devices in the field for which upgrading the booloader is not > an option, neither is changing anything else in the boot process > (anything before linux starts). The risk of bricking the device is > just too high. This is the exact scenario we are solving with the impedance matcher. It's a wrapper around a kernel and a series of dtbs. To the bootloader, it looks _exactly_ like the kernel, but it translates the info passed to it into terms newer kernels can understand. No need for a separate binary. hth, Jason. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
