cross-distro July 2012

cross-distro@lists.linaro.org

5 participants
1 discussions

standard U-Boot environment variables/macros across platforms

by David Marlin

I'm not sure if this has been discussed before, but in working with various ARM systems (Panda, Trim Slice, Highbank, etc.) I have noticed that there is little consistency in the load addresses for kernel, initrd, and device tree, or the commands and devices used. While it may not be practical to always use the same physical addresses, it seems it might be possible to set some 'standard' U-Boot environment variables or macros to provide a more consistent user experience when working on various boards from different vendors. Some vendors already provide U-Boot environment variables for the load addresses, and some for the load commands themselves, but I have not found much consistency between them. One example is the Genesi Efika MX (mx51), which provides: ${loadcmd} ${kerneladdr} ${ramdiskaddr} By providing the kernel and initrd U-Boot images in a boot.scr, you can load and boot the desired kernel with no other board specific knowledge (specific addresses or devices). Highbank provides some similar load address definitions, but with different names, i.e., ${ramdisk_addr_r} ${kernel_addr_r} ${fdt_addr_r} Other boards provide similar features, including some (e.g., Trim-Slice) that 'scan' through a list of devices until a boot.scr is found, load it, and then boot using that script, but the load addresses are literals. Does anyone else think it would be useful to include a 'standard' set of such definitions in U-Boot (default) that could be used to abstract the board/vendor specific details and provide a more consistent user experience? If so, could this list be used to help define such a set, and encourage its use across ARM systems and distros? If this has already been discussed, perhaps someone could provide a link to the thread. Thank you for your consideration, d.marlin

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cross-distro July 2012