On Mon, Sep 30, 2013 at 1:14 PM, Tim Bird <tbird20d@xxxxxxxxx> wrote: > On Tue, Sep 24, 2013 at 5:19 AM, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxxx> wrote: >> On Tue, Sep 24, 2013 at 08:01:52AM -0400, Jason Cooper wrote: >>> On Tue, Sep 24, 2013 at 12:55:19PM +0200, Gerlando Falauto wrote: >>> > So it shouldn't be such a crazy idea to create a dtbuImage.<dtb> >>> > within Kbuild (as opposed to from an external wrapper for make). >>> >>> Yes :) The problem is that we are moving to multiplatform zImages. In >>> that scenario, the uImage target isn't very helpful because it needs to >>> be custom to each board. Additionally, appended-dtb was intended as a >>> developer tool and isn't intended as a deployable item. It also >>> defeats the purpose of multiplatform. >> >> And we've already taken the decision that we will not be augmenting >> kbuild with any more ubooot specific stuff, especially with anything >> that goes against the long term goal of having a single kernel image >> which is bootable across multiple platforms. >> >> Having kbuild wrap the zImage + DTB up into a uImage goes directly >> against this goal, because it turns the produced kernel into something >> which is specific to a single target. It's much worse than what we >> had before we went to DT, because with this it can only be used on a >> _single_ target, whereas prior to DT we could boot a single kernel >> on a variety of compatible targets. >> >> Moreover, the support for appending the DTB to the zImage is a stop-gap >> solution for the transition to a full DT based environment - don't >> expect it to be around into the long term future. Modern platforms >> should be using a DT compatible boot loader, which means you don't >> want to use the DTB appended to zImage method. >> > > What is the long-term mechanism/methodology for creating a kernel > that runs on a single system? So many drivers now have device-tree > dependencies that it seems unlikely we'll be able to avoid using > device tree. But if we don't care or don't want to support more than > a single platform, what should we do (if appending DTB to the zImage > will eventually go away). Will the requirement be that all future > Linux bootloaders will be DT-aware? I don't think appended DTB will go away. In fact, use of it is now being added to flash-kernel in debian/ubuntu. However, this is only done at OS install time on running on the h/w. The problem goes beyond just having a DT aware bootloader. You also need the bootloader to ship with the DTB. This isn't happening yet, so the distros are having to install their own DTB. Since there is not a standard way to install a dtb and tell the bootloader where it is, the appended dtb is the quick solution. Rob -- 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
