On Wed, Nov 13, 2024 at 5:34 AM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote: > > On Tue, Nov 12, 2024 at 7:45 PM Miguel Ojeda <ojeda@xxxxxxxxxx> wrote: > > > > From: HONG Yifan <elsk@xxxxxxxxxx> > > > > These are flags to be passed when linking proc macros for the Rust > > toolchain. If unset, it defaults to $(KBUILD_HOSTLDFLAGS). > > > > This is needed because the list of flags to link hostprogs is not > > necessarily the same as the list of flags used to link libmacros.so. > > When we build proc macros, we need the latter, not the former (e.g. when > > using a Rust compiler binary linked to a different C library than host > > programs). > > > > To distinguish between the two, introduce this new variable to stand > > out from KBUILD_HOSTLDFLAGS used to link other host progs. > > > > Signed-off-by: HONG Yifan <elsk@xxxxxxxxxx> > > Link: https://lore.kernel.org/r/20241017210430.2401398-2-elsk@xxxxxxxxxx > > [ v3: > > > > - `export`ed the variable. Otherwise it would not be visible in > > `rust/Makefile`. > > Despite the missing export, the previous version worked for us too. > I'm not sure why that is. It happened to pass the build when KBUILD_HOSTLDFLAGS was empty, which was the case when it was not exported. But that was definitely not the original intention of this patch. Thanks for catching it! I have verified that v3 correctly exports the variable to sub-make and still works for our case. > > > - Removed "additional" from the documentation and commit message, > > since this actually replaces the other flags, unlike other cases. > > > > - Added example of use case to documentation and commit message. > > Thanks Alice for the details on what Google needs! > > > > - Instead of `HOSTLDFLAGS`, used `KBUILD_HOSTLDFLAGS` as the fallback > > to preserve the previous behavior as much as possible, as discussed > > with Alice/Yifan. Thus moved the variable down too (currently we > > do not modify `KBUILD_HOSTLDFLAGS` elsewhere) and avoided > > mentioning `HOSTLDFLAGS` directly in the documentation. > > > > - Fixed documentation header formatting. > > > > - Reworded slightly. > > > > - Miguel ] > > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > > Tested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> > Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> Reviewed-by: HONG Yifan <elsk@xxxxxxxxxx>
