On Thu, May 23, 2024 at 06:01:49PM GMT, Jarkko Sakkinen wrote:
Hi, I just put this here while I still have it on my mind. Possibly I'm ignoring something that already enables this but at least I learn something by doing this then. This came up in a recent discussion albeit for this crypto bug it did not make waves because the bug fix did not require it: https://lore.kernel.org/linux-integrity/D1GXKODMD4S8.1J12D4GOEQWPL@xxxxxxxxxx/ So the gist of is_module() would be that it would have different semantics than IS_MODULE(): it could be used to e.g. check modules in a loop. Compilation would generate a new ELF section with following entries: <ASCIIZ string><0 or 1> The string would contain module name, and 1 could be marking for being a module, and 0 for being builtin. Also, it would enabled to add lsmod -b to enumerate built-in modules, which would give nice way to carve up more information about a running test kernel. This would obviously need perhaps a new file to procfs for built-in modules (for regular there is /proc/modules).
this information is already exported by kernel's build system: $ head /usr/lib/modules/$(uname -r)/modules.builtin kernel/arch/x86/kernel/msr.ko kernel/arch/x86/kernel/cpuid.ko kernel/arch/x86/platform/intel/iosf_mbi.ko kernel/kernel/configs.ko kernel/mm/zbud.ko kernel/mm/zsmalloc.ko kernel/mm/z3fold.ko kernel/fs/binfmt_misc.ko kernel/fs/binfmt_script.ko kernel/fs/configfs/configfs.ko But I'm not sure if you were intendending to use that inside the kernel as per the other thread you mentioned. libkmod uses the more verbose modules.builtin.modinfo so e.g. `modinfo ext4` works even if ext4 is builtin. We indeed miss a -b flag to lsmod, but that would be an welcome addition. A decade or so ago I was thinking to actually use /sys/module/ to get details about builtin modules. At the time we didn't have modules.builtin. However not all builtin modules create a dir in /sys, only the ones that have module parameters. I was surprised it's still in kmod's TODO file: https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/TODO#n56 Lucas De Marchi
Not fighting for having this, just makig it visible. BR, Jarkko
