Toolchain independence by wom-bat · Pull Request #717 · au-ts/sddf

wom-bat · 2026-05-08T01:02:55Z

Make sddf build more independent of toolchain.
-- fix warnings from gcc
-- improve common.mk so switching toolchains actually rebuilds things

midnightveil · 2026-05-08T01:08:50Z


-REBUILD_CANDIDATE_OBJECTS := $(shell find . -name '*.o')
-${REBUILD_CANDIDATE_OBJECTS): .EXTRA_PREREQS = ${CHECK_FLAGS_BOARD_HASH}
+.EXTRA_PREREQS = ${CHECK_FLAGS_BOARD_HASH}


FYI Peter: #715. (I suspect this might be the BSD make instead of GNU make thing again? IDK)

Could be; I will check this.

We use so many GNUmake idioms I'd be surprised if BSD make builds the system at all.

Is it possible to make make error if it's not GNUmake? That would solve this as well, I think. (I do recall us decided that we basically need GNUmake: our CI needs it explicitly)

Correction: macOS default is GNUmake 3.8, from 2006...

So I don't know what the difference is but @0aids was reporting that $^ was including all the dependencies from this and breaking their build.

I don't know what the difference is between them.

Do you mean with 'EXTRA_PREREQS' or with Courtney's patch? Either way, we're adding a prerequisite to ensure that stuff is rebuilt; and $^ is the list of all prerequisites except the ones in EXTRA_PREREQS -- Courtney's patch will add the hash file 6to the list; this patch will not.

Yes, Courtney's patch. But it also included all the .h files listed in the compiler emitted .d files.

What confuses me is I don't see what the difference is because the list of dependencies in the compiler-depfile would contain the headers always but why does it only sometimes appear in $^. And when we tested this with two files one included the dependencies in the other file didn't appear in $^.

On the first run, the .d files haven't been created, so Make doesn't know about the header files. On subsequent runs it does. A prerequisite in Make terms is any file, that if newer than a target, means the target has to be rebuilt: any header file a C file includes, if changed, means that the .o target needs rebuilding. So the complete prerequisite list for a .o file will always include the C file it is built from, and the transitive closure of header files that that C file includes directly or recursively.

There is almost never a reason to use $^ in a Makefile rule;

Well, a lot of our Makefile rules do...

In some ways I think we need to redo all our Makefiles to be of better quality. At the moment they have a hodegpoge of styles and techniques, but at the same time I don't know of any golden references.

midnightveil · 2026-05-12T22:40:47Z



-IMAGES := blk_driver.elf client.elf blk_virt.elf serial_virt_tx.elf serial_driver.elf
-CFLAGS +=  -Wall -Wno-unused-function -Werror -Wno-unused-command-line-argument \


I can understand wanting to remove these disabled warnings but it has nothing to do with GCC vs Clang... These should be separate commits not squished in with the rest silently.

This is GCC-versus clang ... the arguments are not available for gcc, and the warnings they suppress need to be fixed in-line in the code instead.

GCC doesn't support -Wno-unused-function? but it says it does: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wunused-function (and I'm pretty sure these pre-date clang-as-default).

-Wunused-command-line-argument is the one it doesn't seem to accept... and if we can get rid of them, let's go ...

I don't think we can get rid of -Wunused-command-line-argument unfortunately, there's some issues with the Nix-packaged sysroots, and a few other cases.

Gcc complains about a multi-line // comment. Fix it. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

GCC complained about an unused variable: remove it. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

This means we can get of the -Wno-unused-function compiler arg that is unrecognised by GCC. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Extend the board-hash to include TOOLCHAIN and make it so *everything* depends on it. Make clang the default toolchain Allow parent Makefiles to add to the flags depended on. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Extends flags with NVME and PARTITION so changing them forces a rebuild. Passes down Makefile flags to submake. Reformat slightly for clarity Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

This allows compilation ... there are some debug print helper functions in a block.h header file. -- Mark them inline so they don't get expanded if not used -- Mark them __attribute__((unused) to make sure the compiler doesn't complain. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

to make the style checker happy. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

in mmio.c -- clang complains about unused functions. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Fix style in timer/apb_timer/timer.c blk/mmc/imx/usdhc.c and Makefiles Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

This is now set in common.mk. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

wom-bat marked this pull request as draft May 8, 2026 01:05

midnightveil reviewed May 8, 2026

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midnightveil reviewed May 12, 2026

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wom-bat force-pushed the toolchain_independence branch 3 times, most recently from 55be0f0 to e017a3e Compare May 12, 2026 23:53

wom-bat added 9 commits May 13, 2026 09:54

Fix multi-line comment in apb_timer/timer.c

5078b0b

Gcc complains about a multi-line // comment. Fix it. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Remove unused variable in i2c/libi2c.c

7f958e5

GCC complained about an unused variable: remove it. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Mark usdhc_debug as unused

0f02696

This means we can get of the -Wno-unused-function compiler arg that is unrecognised by GCC. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Make sure things are rebuilt when they should be

16062b3

Extend the board-hash to include TOOLCHAIN and make it so *everything* depends on it. Make clang the default toolchain Allow parent Makefiles to add to the flags depended on. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Allow blk example to build with gcc or clang

c42de5f

Extends flags with NVME and PARTITION so changing them forces a rebuild. Passes down Makefile flags to submake. Reformat slightly for clarity Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Whitespace only changes in timer.c

15d7615

to make the style checker happy. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Delete unused function

1a30591

in mmio.c -- clang complains about unused functions. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

Whitespace only fixes

2bb2ae4

Fix style in timer/apb_timer/timer.c blk/mmc/imx/usdhc.c and Makefiles Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

wom-bat force-pushed the toolchain_independence branch from e017a3e to 2bb2ae4 Compare May 12, 2026 23:54

dumsum reviewed May 22, 2026

View reviewed changes

Comment thread examples/blk/blk.mk Outdated

Remove CLANG default toolchain

385953f

This is now set in common.mk. Signed-off-by: Peter Chubb <Peter.Chubb@unsw.edu.au>

midnightveil mentioned this pull request May 26, 2026

Makefile dependency fix #715

Merged



		IMAGES := blk_driver.elf client.elf blk_virt.elf serial_virt_tx.elf serial_driver.elf
		CFLAGS += -Wall -Wno-unused-function -Werror -Wno-unused-command-line-argument \

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