On Wed, Dec 23, 2009 at 09:29:22AM +0000, Andy Green wrote: > > If you don't step into for example toolchain problems or other crazy > > things... > > Again this is buildroot thinking. The distro provides both the native > and cross toolchains for you. You're going to want to use the same > distro as you normally use on your box so the cross toolchain installs > as a package there. > > If all that's left is the risk of "crazy things" happening well that's > a risk whatever you do or even if you do nothing :-) What I mean is that in the past we had more than once the case that we've found showstopper bugs in upstream gcc, binutils etc. (ARM has much less coverage than x86). It was never a problem in the project, because we actually have been able to port test cases to the latest gcc, reproduc, report to upstream, get it fixed, port it back. That at least implies that you *are* able to rebuild everything (which is possible in both ways, of course). > The only thing I know of that matches "outside the kernel" requirement > is the machine ID that's passed in on ATAG. I agree it's generally > good to have a single build that's multipurpose. Machine ID is a good concept, but doesn't work on everything. What's the machine on a system that consists of a cpu module and a baseboard? Things move into the oftree direction, and I think bootloaders have to deal with that, or there has to be a possibility that an early kernel stage deals with the oftree. But that just moves the hackery-code from the bootloader into the kernel, which is no gain. > On iMX you have to go read IIM to get device info but actually that's > not hard. ... as long as the hardware guys don't decide in their great wisdom to change the meaning of some bits from chip to chip ... > But that device ID will itself alone tell you the on-SoC peripherals > since there's an ID per die; it makes no difference if this expanded > SoC oftree data itself lives in the kernel then. The non-SoC stuff > can just be probed. Off-board devices behind SPI, I2C and chip select busses cannot be probed. You are observing a subset of the embedded universe, and you are right if you limit to it. Bootloaders like barebox or u-boot provide a concept for *all* use cases. rsc -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- 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
