Hello, On Thu, Jan 19, 2017 at 04:31:56PM +0100, Mason wrote: > Do you agree that such boot loader would execute code that is roughly > identical to the one posted for illustration purposes? > 1. find the MAC address to use for eth0 > 2. find the eth0 node in the DT > 3. insert the right prop in the eth0 node yes. > In which case, it seems a waste to add the DT library to the boot > loader, when the operation can be done in Linux, which requires the > DT library anyway. (Additionally, adding DT support to some custom > legacy boot loader might be a complex task.) With this reasoning you can discuss away the bootloader. Linux relies on a bootloader for a reason. It's there to initialize RAM and some further things that Linux might not be able to and provide a machine description to Linux (either in form of a dtb or an ATAG list) such that Linux doesn't need to fiddle with machine specific stuff in early init code. > > c) Adapt the dtb before it is written to the boot medium. > > This is not applicable, as the DTB is not written to the board. Ah, then adapt the dtb before it is put into the tftp folder. > > d) Let the bootloader configure the device and teach the driver to pick > > up the mac from the device's address space. > > I'm not sure what you call "the device" ? The network device. IIRC the fec driver checks if there is something configured in the two registers configuring the MAC before falling back to a random MAC. > > e) Accept that the mac address is random during development, and make > > Userspace configure the MAC address, which is early enough for > > production use. > > During development, some devs configure the DHCP server to provide > a specific uImage and/or rootfs to their board, based on the MAC > address. This scheme would fall apart with a random MAC. > > > Not sure d) is considered ok today, but some drivers have this feature. > > I'd say b) is the best choice. > > In my mind, doing it early in Linux is similar in spirit to doing it > at the boot loader stage, in that it's neatly separated from the rest > of the setup. Sure you can do this. But it won't be accepted mainline for sure. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
