On Thu, 2012-04-05 at 14:11 -0700, Martin Michlmayr wrote: > * Ian Campbell <ijc@hellion.org.uk> [2012-04-05 20:24]: > > Support has been added ot the uypstream kernel for the Dreamplug as a FDT > > machine type. Accordingly the attached patch adds the necessary db enry for > > this class of machines. Please consider applying. > > I'm not the maintainer of flash-kernel anymore and haven't followed DT > in detail so maybe this question is stupid... but: where does the DT > blob come from? Shouldn't flash-kernel embed that into the kernel > image, or do you require a DT compatible u-boot which will pass the DT > to the kernel directly? It requires a u-boot with FDT support, #667680 is my request to add that patch to Debian u-boot. There is an option to include a DTB in the kernel (CONFIG_ARM_APPENDED_DTB) but the warnings in the Kconfig are a bit scary and explicitly say it is for compatibility with non-DT capable bootloaders. I'm working on a patch to include the actual blobs in the relevant kernel image package. > I guess you're using a DT compatible u-boot and I think on the > DreamPlug it's fair enough to require users to upgrade to such a > u-boot. I think so, yes. u-boot as shipped with the dreamplug has a broken machid so you pretty much have to reflash it anyway. The JTAG attachment for the dreamplug is fairly cheap (~£30) and easily available (and the software is in Debian) so reflashing is reasonably safe. > (I have other devices in mind that don't ship with a DT u-boot and > where you cannot easily upgrade u-boot; in those cases flash-kernel > will have to embed the DT blob into the kernel image or something.) For devices which currently use the old system nothing should change, a single kernel image can support both FDT and machid things at the same time. So for example the existing support for Sheevaplugs etc in the kirkwood flavour are unchanged. I guess upstream is forcing all new board ports to use DT, which will certainly be a pain for boards with a non DT bootloader. > Also, does it really say "Machine: Marvell Kirkwood (Flattened Device Tree)"? Yes, it really does say that. I thought it was weird too but grepping around in arch/arm it seems to be a fairly common structure (although things aren't all that consistent) > Is there no way to set the Machine info in /proc/cpuinfo to something > more useful with the use of DT? You mean to dynamically set it to something relevant to the actual board? I don't see anything with a quick grep in the kernel. It certainly seems like it would be a good thing for the kernel to do, I'll ask. > In any case, thanks or working on DreamPlug support! > > P.S. your git patch contains your company address but I guess this > wasn't done on company time. Oops yes, I used one of the faster ARM boards at work to do the build and so I ended up committing it there too. Ian. -- Ian Campbell "With molasses you catch flies, with vinegar you catch nobody." -- Baltimore City Councilman Dominic DiPietro
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