On 04/11/2022 20.08, Simon Glass wrote:
Hi Holger,
On Fri, 4 Nov 2022 at 08:20, Holger Brunck holger.brunck@hitachienergy.com wrote:
Hi Simon, I got no time to try it yet but I have a general comment.
Sometimes it is useful to include a CONFIG option that contains a string. This is hard to do in general, since in many cases it is useful to have the quotes around the string so that, for example:
wouldn't it be cleaner to always convert a Kconfig option which is defined as a string to a string without the double quotes? If someone needs them he could explicitly add them with
bootcmd=run "CONFIG_BOARD_CMD"
Because in my case I have some options I use them to build together the kernel command line I pass to the kernel. Ok I could store them before in an own variable and them use them with ${variable} in the command line. But I think it would be cleaner to always convert a string defined in Kconfig in a string without the quotes. What do you think?
Yes I would prefer that to. I'm not sure how to implement it though. Any thoughts?
I agree that special-casing the RHS containing a single qouted string is a bad idea, it's really hard to understand and explain what the rules are.
Unfortunately, I don't think we can just create a separate version of the config.h header where the quotes are removed and then as Holger suggests rely on including the double quotes when needed, because then the C preprocessor would see "CONFIG_BOARD_CMD" as a string literal, inside which macro expansion is not done.
What we really want is to separate the two uses of the config values: "control" and "data". One use is on conditional lines
#if IS_ENABLED(CONFIG_FOO)
and another is the case of substituting values into RHS values.
It is really convenient to use the C preprocessor for the former. But for the latter, it's kind of overkill, and we could probably just as well implement a simple perl script (or python or whatnot) that would do what we want, including stripping of double quotes from string items before substitution. But adding that as a pre-pre-processor step (only doing substitution on lines not beginning with a #) would break down if anybody uses #include directives, and it's also an annoying extra step and extra script to maintain.
tl;dr: no, I don't have any good ideas.
Rasmus