Wow, no responses for almost two days, does that mean consensus has been reached?
On Wed, May 19, 2010 at 2:22 PM, Nicolas Pitre <[email protected]> wrote: > On Wed, 19 May 2010, Jamie Lokier wrote: > >> Nicolas Pitre wrote: >> > It is not up to the bootloader to "adjust" to the kernel. But rather >> > for the kernel to cope with the bootloader's provided information. If >> > the bootloader passes a specific machine ID with the ATAG list then the >> > kernel will use that, and if the bootloader passes a DT machine ID with >> > a DT blob then the kernel will use that. You just have to configure >> > your kernel with both "machine types" at the same time. >> >> Scenario: >> >> You upgrade your systems to a new DT-capable kernel and DT-capable >> bootloader. It works great. You ship new instances of your device with >> this. >> >> Once they're in the field, someone reports a bug that doesn't happen >> with the older device instances. It's not a bug you can reproduce, >> but you suspect the newer of kernel. So you remote-update some of the >> newly shipped devices with an old, pre-DT kernel binary that's been >> stable on the older devices, to see if the bug goes away. >> >> Problem: The newer shipped devices have a DT-capable bootloader, and >> it can't boot old kernels, because they don't understand the DT format. >> >> You could remote-downgrade the bootloaders, but that's risky. You >> could try building the old kernel with DT support, but that adds >> another variable to your testing. >> >> Anticipating this well in advance, you of course built your DT-capable >> bootloader with the ability to boot old and new style kernels... > > Exact. Quoting myself: > > |I think that, for the moment, it is best if the bootloader on already > |existing subarchitectures where DT is introduced still preserve the > |already existing ability to boot using ATAGs. This allows for the > |testing and validation of the DT concept against the legacy ATAG method > |more easily. > | > |On new subarchitectures, it might make sense to go with DT from the > |start instead of creating setup code for every single machine. In that > |case the bootloader for those machines would only need to care about DT > |and forget about ATAGs. > > > Nicolas > _______________________________________________ > devicetree-discuss mailing list > [email protected] > https://lists.ozlabs.org/listinfo/devicetree-discuss > _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
