On Sat, May 20, 2023 at 1:21 PM <masahiroy@xxxxxxxxxx> wrote: > > On Thu, May 18, 2023 at 4:13 PM <sunying@xxxxxxxxxxxxxx> wrote: > > > > Hi, > > > > > > We found that the Kconfig build system silently changes invalid values in the. config file, > > which may prevent users from getting their desired kernel, and also make it hard to know > > which configuration option caused the forced change based on the compilation information. > > > > There are similar questions on stack overflow, where people find it difficult to get > > the complete dependency chain and other information： > > > > ex1. How can I disable CONFIG_PM when building Linux kernel for x86_64 - Stack Overflow > > https://stackoverflow.com/questions/64499221/how-can-i-disable-config-pm-when-building-linux-kernel-for-x86-64/64501647#64501647 > > > > ex2. c - kernel symbol enabled but doesn't shows up in .config - Stack Overflow > > https://stackoverflow.com/questions/24074116/kernel-symbol-enabled-but-doesnt-shows-up-in-config) > > > > ex3. makefile - update menuconfig entries without recompiling all the kernel - Stack Overflow > > https://stackoverflow.com/questions/71075113/update-menuconfig-entries-without-recompiling-all-the-kernel > > > > ex4. linux - disabling CONFIG_NET_DMA - Stack Overflow > > https://stackoverflow.com/questions/30794576/disabling-config-net-dma/30796820#30796820 > > > > We plan to optimize the conf_read() function in /scripts/kconfig/confdata.c, > > and add information for the mismatched configuration options to help users get the desired Linux kernel. > > Do you think it's necessary? Any suggestions? > > > > > It may be helpful. > I do not know if such warnings should be turned on by default, > or under some verbose mode, though. > Can we reuse "KBUILD_VERBOSE" switch to print more warning? By default, a message is added as follows only when invalid values in .config are detected: "warning: values in .config are forcibly modified to meet the kconfig dependency constraints. For more information, enable the environment variable 'export KBUILD_VERBOSE=1'." In verbose mode, print invalid configuration options one by one, including error causes and current values, to help users correct them. For example, in the case of ex1. above, we can prompt with the following message: "file:line: warning: 'CONFIG_PM' reverse select error, due to 'CONFIG_PM_SLEEO' is set to 'y'." Do you think this would work? Can we modify it in this way? > > Best regards, > > Siyuan Guo > > Ying Sun > > > > > > > -- > Best Regards > Masahiro Yamada -- Best regards, Siyuan Guo Ying Sun </sunying@xxxxxxxxxxxxxx></masahiroy@xxxxxxxxxx>
