Hi Simon, On Monday 01 August 2011 07:43 PM, Simon Schwarz wrote: > Hi Aneesh, > > On 08/01/2011 02:56 PM, Aneesh V wrote: >> Hi Simon, >> >> On Monday 01 August 2011 04:50 PM, Simon Schwarz wrote: >>> Hi Aneesh, >>> >>> I am working on the OS booting right now and have a bigger change of >>> your code in spl.c in mind. >>> >>> Hope you can say one or two words what you think about it. >>> >>> THE PROBLEM >>> For the direct OS boot and in some other situations - env image e.g., I >>> have to load more than one image in SPL. >>> >>> This can be done by hardcoding these cases and use #ifdef or ifs to >>> switch between them. Or I can implement a general image loading with >>> lists. >>> (This was discussed here: >>> http://article.gmane.org/gmane.comp.boot-loaders.u-boot/102345) >> >> At the outset, wonder why we can not use the default bootargs string in >> the kernel image instead of passing it from the bootloader. For direct >> kernel boot from SPL, that looks like the best option for me. Then we >> will not need all this. Am I missing something? >> > From the documentation it is mandatory for ARM to pass ATAGS (or FDT I > assume): http://www.arm.linux.org.uk/developer/booting.php > > So I think your solution would work - but IMHO would be too simple. > > The beauty is that we can save the config of ATAGS/FDT directly in > u-boot and pass this image at the next boot to the SPL. This means we > can boot the exact same configuration with the SPL as with standard > u-boot - without recompiling the kernel. Trade-off: a more complex SPL.
If my suggestion works I would still prefer that. If you want better configurability you can always use u-boot! Direct kernel boot from SPL is likely to be used in production systems for improved boot-time, where it should be OK to hard-code the boot-args. Using u-boot seems to be a better option if changing bootargs frequently is a requirement. Please note that any scheme that you comes up with should also work for FAT boot from SD/MMC card, which means you need to have a way of converting your ATAGS list into a file, reading it and so on. A lot of trouble without much value-add in my opinion(assuming that hard-coded bootargs works). In the worst case I would prefer hard-coding bootargs in SPL in a config flag and using it to build the list in SPL. I would love to hear others' views on this. best regards, Aneesh _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
