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Homebrew AVR Toolchain
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New tiny (atxmega3 core) such as ATtiny817 seem to be missing #176

Closed burnpanck closed 3 years ago

burnpanck commented 4 years ago

Since AVR-GCC 8, the new tiny are supported: https://gcc.gnu.org/gcc-8/changes.html If I do a find /usr/local/Cellar/avr-gcc -iname "*attiny817*" I do get the following:

/usr/local/Cellar/avr-gcc/9.2.0_1/lib/avr-gcc/9/gcc/avr/9.2.0/device-specs/specs-attiny817

That specs file refers to a crtattiny817.o which seems to be missing. If I instead search e.g. for the "ATxmega64a3u", I get

/usr/local/Cellar/avr-gcc/9.2.0_1/avr/lib/avrxmega4/libatxmega64a3u.a
/usr/local/Cellar/avr-gcc/9.2.0_1/avr/lib/avrxmega4/crtatxmega64a3u.o
/usr/local/Cellar/avr-gcc/9.2.0_1/lib/avr-gcc/9/gcc/avr/9.2.0/device-specs/specs-atxmega64a3u

In fact, /usr/local/Cellar/avr-gcc/9.2.0_1/avr/lib/avrxmega3 seems to be completely missing.

ladislas commented 4 years ago

In your example you're using avr-gcc 9.2.0.

Have you tried installing avr-gcc 8.x.x to see if it works?

brew install avr-gcc@8
burnpanck commented 4 years ago

I had not, as support for new devices is usually cumulative; no reason to remove support for recent devices after they have just been added. Also, the presence of the specs file indicates that GCC thinks that the device is supported - the install is just broken in that it does not contain all the necessary files.

Anyway, I have now tried it withavr-gcc@8 and I do get the exact same picture:

~ find  /usr/local/Cellar/avr-gcc@8/ -iname "*attiny817*"  
/usr/local/Cellar/avr-gcc@8//8.3.0_1/lib/avr-gcc/8/gcc/avr/8.3.0/device-specs/specs-attiny817

versus e.g.

~ find  /usr/local/Cellar/avr-gcc@8/ -iname "*atxmega64a3u*"
/usr/local/Cellar/avr-gcc@8//8.3.0_1/avr/lib/avrxmega4/libatxmega64a3u.a
/usr/local/Cellar/avr-gcc@8//8.3.0_1/avr/lib/avrxmega4/crtatxmega64a3u.o
/usr/local/Cellar/avr-gcc@8//8.3.0_1/lib/avr-gcc/8/gcc/avr/8.3.0/device-specs/specs-atxmega64a3u
burnpanck commented 4 years ago

To be concrete, compilation of a simple empty loop main() with avr-g++ -mmcu=attiny817 main.cpp -o main.elf fails as follows:

/usr/local/opt/avr-binutils/bin/avr-ld: cannot find crtattiny817.o: No such file or directory
/usr/local/opt/avr-binutils/bin/avr-ld: skipping incompatible /usr/local/Cellar/avr-gcc/9.2.0_1/lib/avr-gcc/9/gcc/avr/9.2.0/../../../../../../avr/lib/libm.a when searching for -lm
/usr/local/opt/avr-binutils/bin/avr-ld: cannot find -lm
/usr/local/opt/avr-binutils/bin/avr-ld: skipping incompatible /usr/local/Cellar/avr-gcc/9.2.0_1/lib/avr-gcc/9/gcc/avr/9.2.0/../../../../../../avr/lib/libm.a when searching for -lm
/usr/local/opt/avr-binutils/bin/avr-ld: cannot find -lm
/usr/local/opt/avr-binutils/bin/avr-ld: skipping incompatible /usr/local/Cellar/avr-gcc/9.2.0_1/lib/avr-gcc/9/gcc/avr/9.2.0/../../../../../../avr/lib/libc.a when searching for -lc
/usr/local/opt/avr-binutils/bin/avr-ld: cannot find -lc
/usr/local/opt/avr-binutils/bin/avr-ld: cannot find -lattiny817
collect2: error: ld returned 1 exit status

The same file compiles successfully with e.g. -mmcu=atxmega64a3u. Compilation against a random unsupported MCU fails differently:

~ avr-g++ -mmcu=atdoesnotexist1 main.cpp -o main.elf
avr-g++: fatal error: cannot read spec file 'device-specs/specs-atdoesnotexist1': No such file or directory
compilation terminated.
ladislas commented 4 years ago

It might be the same kind of issue than the ones #105 fixed. I've also found this, maybe it can be helpful:

https://savannah.nongnu.org/patch/?9543

Could you try the patch and if it works make a PR? The one I referenced is a good example.

Feuerwerk commented 4 years ago

Hi

If you need help i can support.

Greetings Chris

ladislas commented 4 years ago

Thanks a lot @Feuerwerk! :)

burnpanck commented 4 years ago

@ladislas: Thanks for identifying the patch! So it really seems like an upstream bug, not a packaging problem. Unfortunately, I'm quite tight on time these days. I probably won't be able to give it a try before April.

metropt commented 4 years ago

I found the same today when I tried to use avr-gcc 5.5. With avr-gcc 8+ it is working.

ze-mac:Downloads ze$ avr-gcc -v
Using built-in specs.
Reading specs from /usr/local/Cellar/avr-gcc@5/5.5.0/lib/avr-gcc/5/gcc/avr/5.5.0/device-specs/specs-avr2
COLLECT_GCC=avr-gcc
COLLECT_LTO_WRAPPER=/usr/local/Cellar/avr-gcc@5/5.5.0/libexec/gcc/avr/5.5.0/lto-wrapper
Target: avr
Configured with: ../configure --target=avr --prefix=/usr/local/Cellar/avr-gcc@5/5.5.0 --libdir=/usr/local/Cellar/avr-gcc@5/5.5.0/lib/avr-gcc/5 --enable-languages=c,c++ --with-ld=/usr/local/opt/avr-binutils/bin/avr-ld --with-as=/usr/local/opt/avr-binutils/bin/avr-as --disable-nls --disable-libssp --disable-shared --disable-threads --disable-libgomp --with-dwarf2
Thread model: single
gcc version 5.5.0 (GCC)
ze-mac:Downloads ze$ avr-gcc -mmcu=attiny202 -B ~/Downloads/Atmel.ATtiny_DFP.1.4.310/gcc/dev/attiny202 -I ~/Downloads/Atmel.ATtiny_DFP.1.4.310/include/ -x c -c -DATtiny202  -funsigned-char -funsigned-bitfields -O1 -ffunction-sections -fdata-sections -fpack-struct -fshort-enums -Wall -o main.o main.c
main.c:1:0: error: unknown core architecture 'avrxmega3' specified with '-mmcu='
 /*
 ^
main.c:1:0: note: supported core architectures: avr2 avr25 avr3 avr31 avr35 avr4 avr5 avr51 avr6 avrxmega2 avrxmega4 avrxmega5 avrxmega6 avrxmega7 avrtiny avr1
ze-mac:Downloads ze$
burnpanck commented 4 years ago

That seems like a different issue to me. The new atxmega3 have really been added to avr-gcc around version 8 as you observed. The issue I encountered was in fact in avr-libc, where those devices are still not supported, except for a hanging pull-request. So I'm surprised that you say it does work for you with avr-gcc 8. Could you post the command-line you used there? I do note that you add include paths to some Atmel download related to DFPs - could it be possible that the missing crt files are found there? Also, are you using the upstream avr-gcc or the Atmel distribution?

metropt commented 4 years ago

The Atmel toolchain comes with GCC 5.4.0 https://www.microchip.com/mplab/avr-support/avr-and-arm-toolchains-c-compilers and I can run the above code. From what I understand you can give the compiler a device_specs with -B.

avr-gcc@8 works if I pass the -B option.

burnpanck commented 4 years ago

Hey @metropt, thank you for your answer! Could you nonetheless please post the exact full command-line that did work for you?

Note that the -B flag does not actually set device specs, but rather it prepends a number of directories to the compiler's search paths in the various build passes - including when looking for specs.

I was able to download the device pack from atmel from packs.download.atmel.com. With that, I was able to compile my source with a command-line as follows:

avr-g++ -Batmel-DFP/gcc/dev/attiny817 -Iatmel-DFP/include  -Os -save-temps -g -gdwarf-3 -gstrict-dwarf -fno-exceptions   -mmcu=attiny817 -std=gnu++17 -o main.cpp.obj -c main.cpp

However, this does only compile (-c flag), so it will never show the link problems I posted above. If I try 

avr-g++ -Batmel-DFP/gcc/dev/attiny817 -Iatmel-DFP/include  -Os -save-temps -g -gdwarf-3 -gstrict-dwarf -fno-exceptions   -mmcu=attiny817 -std=gnu++17 -o main.elf main.cpp

instead, the missing crtattiny817.o and libattiny817 are indeed found, but I still get skipping incompatible ... for -lm and -lc.

Indeed, gcc tries to locate libm.a and libc.a in the usual way, and only finds those for other architectures (because avrxmega3 is currently missing from avr-libc). Of course, within atmel's gcc 5.4 download, there are also libm.a and libc.a for avrxmega3. Maybe these are the ones your build found? In any case, the approach here is re-using binaries downloaded from unknown origin (atmel) - it might very well not work together with our version of gcc and lead to silently and fatally failing code.

ladislas commented 4 years ago

I would avoid at all costs mixing toolchains. Either go all the way with Atmel toolchain or with with this one.

metropt commented 4 years ago

Thank you, with this toolchain I'm able to build the code only with GCC 9+, is that correct?

luqasz commented 4 years ago

GCC 10 added some of them:

ATtiny202, ATtiny204, ATtiny402, ATtiny404, ATtiny406, ATtiny804, ATtiny806, ATtiny807, ATtiny1604, ATtiny1606, ATtiny1607, ATmega808, ATmega809, ATmega1608, ATmega1609, ATmega3208, ATmega3209, ATmega4808, ATmega4809

burnpanck commented 4 years ago

@luqasz: GCC 8 added the 1-series long before:

The AVR port now supports the following XMEGA-like devices: ATtiny212, ATtiny214, ATtiny412, ATtiny414, ATtiny416, ATtiny417, ATtiny814, ATtiny816, ATtiny817, ATtiny1614, ATtiny1616, ATtiny1617, ATtiny3214, ATtiny3216, ATtiny3217 The new devices are listed under -mmcu=avrxmega3.

The problem discussed in this issue is that avr-libc, which is a separate project often bundled with avr-gcc (for example here in this homebrew package), was last released at version 2.0 four years ago and therefore does not support those new devices.

@ladislas has identified an open patch to libc adding that support, which, after my failed previous attempts to include here, have recently been updated.

Now, the chances might be much better - someone just needs to find the time for it :-).

ladislas commented 3 years ago

Any news on this? I'll close the issue for now, feel free to reopen and submit a PR. :)