On Tue, Jun 02, 2009 at 11:29:46AM -0600, Grant Likely wrote: > On Tue, Jun 2, 2009 at 9:22 AM, James Bottomley > <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > > Hi All, > > > > We've got to the point where there are simply too many embedded > > architectures to invite all the arch maintainers to the kernel summit. > > So, this year, we thought we'd do embedded via topic driven invitations > > instead. So what we're looking for is a proposal to discuss the issues > > most affecting embedded architectures, or preview any features affecting > > the main kernel which embedded architectures might need ... or any other > > topics from embedded architectures which might need discussion or > > debate. If you'd like to do this, could you either reply to this email, > > or send proposals to: > > > > ksummit-2009-discuss@xxxxxxxxxxxxxxxxxxxxxxxxxx > > Hi James, > > One topic that seems to garner debate is the issue of decoupling the > kernel image from the target platform. ... > Embedded PowerPC and Microblaze has tackled this problem with the > "Flattened Device Tree" data format which is derived from the > OpenFirmware specifications, and there is some interest and debate (as > discussed recently on the ARM mailing list) about making flattened > device tree usable by ARM also (which I'm currently > proof-of-concepting). Josh Boyer has already touched on discussing > flattened device tree support at kernel summit in an email to the > ksummit list last week (quoted below), and I'm wondering if a broader > discussing would be warranted. I absolutely agree with this. We have been using the flattened device tree on our MIPS platform to support multiple systems, and are close to posting a patch to the MIPS Linux mailing list. At least one other MIPS platform has indicated that they want to use the device tree. > I think that in the absence of any established standard like the PC > BIOS/EFI or a real Open Firmware interface, then the kernel should at > least offer a recommended interface so that multiplatform kernels are > possible without explicitly having the machine layout described to it > at compile time. I know that some of the embedded distros are > interested in such a thing since it gets them away from shipping > separate images for each supported board. ie. It's really hard to do > a generic live-cd without some form of multiplatform. FDT is a great > approach, but it probably isn't the only option. It would be worth > debating. Is there another possibility besides the device tree that people are using on 4 different architectures? We can't mandate support of the device tree for any particular architecture or platform, but we can make sure the device tree infrastructure is supported well enough that any architecture can pick it up easily. Doing so will also encourage support in bootloaders which may not currently do so. Should we decide to go this way, there probably a next step wherein we standardize the device tree entries for those devices that are shared across multiple architectures and platorms. This will likely be a never-ending and mostly thankless task, but will again make things easier in the long run. > Grant Likely, B.Sc., P.Eng. > Secret Lab Technologies Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
