Hi Wolfgang, On Mon, 19 Oct 2020 at 08:55, Wolfgang Denk <w...@denx.de> wrote: > > Dear Simon, > > In message <20201019135602.3943835-12-...@chromium.org> you wrote: > > In some cases it is necessary to pass parameters to Linux so that it will > > boot correctly. For example, the rootdev parameter is often used to > > specify the root device. However the root device may change depending on > > whence U-Boot loads the kernel. At present it is necessary to build up > > the command line by adding device strings to it one by one. > > > > It is often more convenient to provide a template for bootargs, with > > U-Boot doing the substitution from other environment variables. > > > > Add a way to substitute strings in the bootargs variable. This allows > > things like "rootdev=%U" to be used in bootargs, with the %U substitution > > providing the UUID of the root device. > > Argh, no, please don't. > > You add something unconditionally to common code which very few > people need. U-Boot size is growing all the time because of such > ... features. This may be acceptable on the systems you have in > mind, but I consider this selfish.
Did you see the Kconfig option? > > Why do we have to add yet another non-standard way of substituting > variables in a string? Can we not use alreay existing methonds > instead? What sort of methods? > > Why do you have to use "%U" in your template instead of for example > "${uuid}" ? This is what Chrome OS uses, so it is easier this way, Otherwise I have to replace %U with ${uuid} first. Which code can I use to parse the ${var} thing? Regards, Simon