On 10/24/2012 01:32 PM, Tom Rini wrote: > On Wed, Oct 24, 2012 at 01:05:16PM -0600, Stephen Warren wrote: >> On 10/24/2012 12:41 PM, Tom Rini wrote: ... >>> Doing something to derive this also means that custom >>> development can be a bit easier too since you can just set >>> fdtfile directly and work out the logic for auto-detection >>> later. >> >> Hmm. So I can't really put the following into Tegra's default >> environment: >> >> "fdtfile=${soc}-${board}${boardrev}.dtb" >> >> ... since that would require any use of "${fdtfile}" in a command >> to first expand fdtfile itself, then expand it a second time to >> pick up the actual soc/board/... values, and that's not how the >> shell works. >> >> That implies that e.g. Tegra's scriptboot (seed BOOTCMDS_COMMON >> in include/configs/tegra-common-post.h) would need to do >> something like: >> >> setenv fdtfile ${soc}-${board}${boardrev}.dtb > > I hope that a longer term thing would be trying to share more of > the bootcmd related magic between all our parts. How we deal with > this on TI stuff is that in uEnv.txt if we find the file, we load > the file into the environment (so fdtfile=mylocalstuff.dtb will > overwrite the default) and if uenvcmd is set execute that command.
Ah, so uEnv.txt is some user-managed file along the same lines as boot.scr. I had thought it was the file behind CONFIG_ENV_IS_IN_FAT. >> ... before executing the loaded boot.scr. But then, how would it >> know whether to do that, or whether the user wanted to override >> the fdtfile value? >> >> In theory, I could do the following in Tegra's default >> environment: >> >> "fdtfile=" CONFIG_SYS_SOC "-" CONFIG_SYS_BOARD" ".dtb" >> >> But then that wouldn't allow for the fdtfile value to vary at >> run-time based on $boardrev. > > It's not an imutable variable, so you could change it, if you do > that early in the process. Sure. My point was that would end up duplicating the method to construct the value in two places; one in includes/configs/xxx.h for the default, and one in code in U-Boot for the case where we override the default to include some version number. That doesn't seem ideal. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot