SIM card related Projects » SIMtrace 2

I actually gave clang a try, there is https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm which conveniently builds clang and compiler-rt and newlib. Of course any distro provided clang package would work as well for compiling, but the issue is that we need a stdlib and compiler runtime as well, so just running that script is the most convenient way to get all of that (until oom, pass --parallel=x). Still needs binutils, but i just used my existing arm gcc package for that to give it a try.

The -Os binaries are about as large as the gcc versions

16324 Okt 13 19:45 firmware/bin/ngff_cardem-dfu-flash.bin
15484 Okt 13 19:45 firmware/bin/qmod-dfu-flash.bin
15104 Okt 13 19:45 firmware/bin/simtrace-dfu-flash.bin

but clang does have a -Oz that offers smaller code:

14704 Okt 13 19:50 firmware/bin/ngff_cardem-dfu-flash.bin
13996 Okt 13 19:50 firmware/bin/qmod-dfu-flash.bin
13612 Okt 13 19:50 firmware/bin/simtrace-dfu-flash.bin

The gcc last toolchain I used that "just works" was gcc-arm-none-eabi-9-2020-q2-update - tho I do remember having size issues some time last year with a slightly older one..

Clang support in https://gerrit.osmocom.org/c/simtrace2/+/25849 I'd propose to just build the firmware with clang, and that's it.
As for reporting, I don't really know what to report - after all at the time having a bootloader that barely was able to fit into 16k was fine, but continuously rebuilding and modifying it and expecting the optimizer performance to keep the size without adding a few bytes here and there was not really a reasonable assumption.

Hoernchen wrote in #note-1:

I actually gave clang a try, there is https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm which conveniently builds clang and compiler-rt and newlib. Of course any distro provided clang package would work as well for compiling, but the issue is that we need a stdlib and compiler runtime as well, so just running that script is the most convenient way to get all of that (until oom, pass --parallel=x). Still needs binutils, but i just used my existing arm gcc package for that to give it a try.

I've attempted to build llvm with the linked scripts, however building took a very long time. I didn't measure the time unfortunately, but I think I let it run for more than an hour before I aborted it. Unless we really want to build it from source, I suggest we use binary packages instead.

Apparently there will be official binary packages from the project available in coming days, so I'll wait for them: https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm/issues/79

These patches add the binary release of LLVM-embedded-toolchain-for-Arm to the docker image we use in jenkins, and enables USE_CLANG=1:

https://gerrit.osmocom.org/q/topic:simtrace2-llvm

Patch is merged, marking as resolved.

The "report this size regression to upstream gcc" checkbox is still unchecked, but this was commented on in #note-2.