On Mon, Sep 21, 2026 at 03:50:06PM +0200, Petr Pavlu wrote: > On 9/21/26 2:48 PM, Lorenzo Stoakes (ARM) wrote: > > On Mon, Sep 21, 2026 at 02:36:30PM +0200, Petr Pavlu wrote: > >> On 9/21/26 1:57 PM, Lorenzo Stoakes (ARM) wrote: > >>> (note there's a v3 see [0]) > >>> > >>> [0]: > >>> https://lore.kernel.org/linux-kbuild/[email protected]/ > >> > >> Thanks, I missed it. > >> > >>> On Mon, Sep 21, 2026 at 01:25:09PM +0200, Petr Pavlu wrote: > >>>> On 9/14/26 11:22 AM, Lorenzo Stoakes (ARM) wrote: > >>>>> The sections were confirmed to be byte-for-byte identical to the C > >>>>> version > >>>>> produced - each of .modinfo, .gnu.linkonce.this_module, __ksymtab*, > >>>>> __ksymtab_strings, __kcrctab*, __kflagstab*, __versions, > >>>>> __version_ext_crcs, __version_ext_names and their relocations - for all > >>>>> 8,135 modules of a clang allmodconfig build with CONFIG_COMPILE_TEST off > >>>>> and CONFIG_MODVERSIONS, CONFIG_EXTENDED_MODVERSIONS and > >>>>> CONFIG_MODULE_SRCVERSION_ALL on, and for a sample built with gcc. > >>>> > >>>> Lowering the data to assembly loses debug information for __this_module, > >>>> specifically that it has type `struct module`. It might be worth > >>> > >>> No, it keeps it - every module includes linux/module.h, and the extern > >>> declaration of __this_module carries the type, so all of the stuff gdb > >>> needs (e.g. ptype, p & field access), DWARF etc. is all there in the same > >>> way as with .mod.c. > >>> > >>> Have confirmed locally. > >> > >> An extern declaration alone shouldn't cause its name and type to be > >> included in debug information. They should appear only when the variable > >> is referenced by some code. > > > > Ack yeah sorry my mistake, I had the LLM check that and should have known > > better than to trust it without reviewing what it said (as I have done for > > the most part for everything in this series). > > > >> > >> Testing with a simple module that previously referenced __this_module > >> only in .mod.c and in no other file, such as lib/test_module.c, shows > >> that the .ko no longer contains debug information for this variable. > >> > >> I've verified this behavior with GCC 16 and Clang 19. > > > > Ack confirmed locally. > > > > Can put a fix in module-common.c. > > > > The LLM came up with a reference as an alternative: > > > > static struct module *const __this_module_dbg __used > > __section(".discard.this_module") = &__this_module; > > > > Would that work? Or should we go with your original suggestion? - > > > > __weak __section(".discard.this_module") struct module __this_module; > > With GCC, the LLM's suggestion produces debug information for both > __this_module_dbg and __this_module. However, Clang only generates debug > information for __this_module_dbg, so it is not quite what is needed.
Ack will go with your suggestion then, thanks! Will be applied to v4. I am aiming for ~midweek for sending that that out to give people a chance to respond and because it'll be based on other pending commits that need a bit of time before they're in-tree. I have added you to the cc-list so you should get mailed when I send it out! Thanks for the feedback :) > > -- > Thanks, > Petr -- Cheers, Lorenzo
