avr-gcc toolchain for newer avr device families

[AasmundN]

I am setting up an environment (in neovim) for working with the newer AVR device families (specifically avr128db48). avr-gcc does not support these out of the box and an additional device family pack (DFP) must be installed. I have no problem compiling my program:

#include <avr/io.h>

int main(void) { 
  return 0; 
}

However, clangd gives me the following error when trying to goto definition of avr/io.h

clangd: -32001: invalid AST

I am using the --query-driver option, and when using devices that are supported directly by avr-gcc (such as atmega4809) it works as expected.

The issue seems to arrise in relation to the -B compiler option.

Logs
LspLog

[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:03.655] <-- textDocument/signatureHelp(5)\nI[18:33:03.655] --> reply:textDocument/signatureHelp(5) 0 ms, error: Failed to parse includes\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:03.707] ASTWorker building file /Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c version 9 with command \n[/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/build]\n/Users/aasmundnorsett/Library/avr-toolchain/bin/avr-gcc -DF_CPU=3333333 -DNDEBUG -D__AVR_DEV_LIB_NAME__=avr128db48 -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/include -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src -O3 -DNDEBUG -std=gnu11 -Werror -Wall -Wextra -Wpedantic -Wshadow -Wno-array-bounds -Wno-vla -Os -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/device_pack/include -B/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/device_pack/gcc/dev/avr128db48 -o CMakeFiles/lab4.dir/src/main.c.obj -c -Wno-unknown-warning-option -mmcu=avr128db48 -isystem /Users/aasmundnorsett/Library/avr-toolchain/bin/../lib/gcc/avr/7.3.0/include-fixed -isystem /Users/aasmundnorsett/Library/avr-toolchain/bin/../lib/gcc/avr/7.3.0/../../../../avr/include --target=avr -resource-dir=/Users/aasmundnorsett/.local/share/nvim/mason/packages/clangd/clangd_19.1.0/lib/clang/19 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -- /Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"E[18:33:03.708] Failed to prepare a compiler instance: valid target CPU values are: avr1, at90s1200, attiny11, attiny12, attiny15, attiny28, avr2, at90s2313, at90s2323, at90s2333, at90s2343, attiny22, attiny26, at86rf401, at90s4414, at90s4433, at90s4434, at90s8515, at90c8534, at90s8535, avr25, ata5272, ata6616c, attiny13, attiny13a, attiny2313, attiny2313a, attiny24, attiny24a, attiny4313, attiny44, attiny44a, attiny84, attiny84a, attiny25, attiny45, attiny85, attiny261, attiny261a, attiny441, attiny461, attiny461a, attiny841, attiny861, attiny861a, attiny87, attiny43u, attiny48, attiny88, attiny828, avr3, at43usb355, at76c711, avr31, atmega103, at43usb320, avr35, attiny167, at90usb82, at90usb162, ata5505, ata6617c, ata664251, atmega8u2, atmega16u2, atmega32u2, attiny1634, avr4, atmega8, ata6289, atmega8a, ata6285, ata6286, ata6612c, atmega48, atmega48a, atmega48pa, atmega48pb, atmega48p, atmega88, atmega88a, atmega88p, atmega88pa, atmega88pb, atmega8515, atmega8535, atmega8hva, at90pwm1, at90pwm2, at90pwm2b, at90pwm3, at90pwm3b, at90pwm81, avr5, ata5702m322, ata5782, ata5790, ata5790n, ata5791, ata5795, ata5831, ata6613c, ata6614q, ata8210, ata8510, atmega16, atmega16a, atmega161, atmega162, atmega163, atmega164a, atmega164p, atmega164pa, atmega165, atmega165a, atmega165p, atmega165pa, atmega168, atmega168a, atmega168p, atmega168pa, atmega168pb, atmega169, atmega169a, atmega169p, atmega169pa, atmega32, atmega32a, atmega323, atmega324a, atmega324p, atmega324pa, atmega324pb, atmega325, atmega325a, atmega325p, atmega325pa, atmega3250, atmega3250a, atmega3250p, atmega3250pa, atmega328, atmega328p, atmega328pb, atmega329, atmega329a, atmega329p, atmega329pa, atmega3290, atmega3290a, atmega3290p, atmega3290pa, atmega406, atmega64, atmega64a, atmega640, atmega644, atmega644a, atmega644p, atmega644pa, atmega645, atmega645a, atmega645p, atmega649, atmega649a, atmega649p, atmega6450, atmega6450a, atmega6450p, atmega6490, atmega6490a, atmega6490p, atmega64rfr2, atmega644rfr2, atmega16hva, atmega16hva2, atmega16hvb, atmega16hvbrevb, atmega32hvb, atmega32hvbrevb, atmega64hve, atmega64hve2, at90can32, at90can64, at90pwm161, at90pwm216, at90pwm316, atmega32c1, atmega64c1, atmega16m1, atmega32m1, atmega64m1, atmega16u4, atmega32u4, atmega32u6, at90usb646, at90usb647, at90scr100, at94k, m3000, avr51, atmega128, atmega128a, atmega1280, atmega1281, atmega1284, atmega1284p, atmega128rfa1, atmega128rfr2, atmega1284rfr2, at90can128, at90usb1286, at90usb1287, avr6, atmega2560, atmega2561, atmega256rfr2, atmega2564rfr2, avrxmega2, atxmega16a4, atxmega16a4u, atxmega16c4, atxmega16d4, atxmega32a4, atxmega32a4u, atxmega32c3, atxmega32c4, atxmega32d3, atxmega32d4, atxmega32e5, atxmega16e5, atxmega8e5, avrxmega4, atxmega64a3, atxmega64a3u, atxmega64a4u, atxmega64b1, atxmega64b3, atxmega64c3, atxmega64d3, atxmega64d4, avrxmega5, atxmega64a1, atxmega64a1u, avrxmega6, atxmega128a3, atxmega128a3u, atxmega128b1, atxmega128b3, atxmega128c3, atxmega128d3, atxmega128d4, atxmega192a3, atxmega192a3u, atxmega192c3, atxmega192d3, atxmega256a3, atxmega256a3u, atxmega256a3b, atxmega256a3bu, atxmega256c3, atxmega256d3, atxmega384c3, atxmega384d3, avrxmega7, atxmega128a1, atxmega128a1u, atxmega128a4u, avrtiny, attiny4, attiny5, attiny9, attiny10, attiny20, attiny40, attiny102, attiny104, avrxmega3, attiny202, attiny402, attiny204, attiny404, attiny804, attiny1604, attiny406, attiny806, attiny1606, attiny807, attiny1607, attiny212, attiny412, attiny214, attiny414, attiny814, attiny1614, attiny416, attiny816, attiny1616, attiny3216, attiny417, attiny817, attiny1617, attiny3217, attiny1624, attiny1626, attiny1627, atmega808, atmega809, atmega1608, atmega1609, atmega3208, atmega3209, atmega4808, atmega4809\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:03.708] --> textDocument/publishDiagnostics\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"E[18:33:03.708] Could not build a preamble for file /Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c version 9: CreateTargetInfo() return null\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"E[18:33:03.708]   error: unknown target CPU 'avr128db48'\nI[18:33:03.708] --> workspace/semanticTokens/refresh(3)\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:03.708] Skipping rebuild of the AST for /Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c, inputs are the same.\nI[18:33:03.708] --> textDocument/publishDiagnostics\n"
[ERROR][2024-11-13 18:33:03] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:03.708] <-- reply(3)\n"
[ERROR][2024-11-13 18:33:05] .../vim/lsp/rpc.lua:770	"rpc"	"/Users/aasmundnorsett/.local/share/nvim/mason/bin/clangd"	"stderr"	"I[18:33:05.548] <-- textDocument/definition(6)\nI[18:33:05.548] --> reply:textDocument/definition(6) 0 ms, error: invalid AST\n"

LspInfo

LSP configs active in this buffer (bufnr: 1) ~
- Language client log: ~/.local/state/nvim/lsp.log
- Detected filetype: `c`
- 1 client(s) attached to this buffer
- Client: `clangd` (id: 7, bufnr: [1])
  root directory:    ~/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/
  filetypes:         c, cpp, objc, objcpp, cuda, proto
  cmd:               ~/.local/share/nvim/mason/bin/clangd --query-driver=/Users/aasmundnorsett/Library/avr-toolchain/bin/avr-gcc
  version:           `clangd version 19.1.0 (https://github.com/llvm/llvm-project a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)`
  executable:        true
  autostart:         true

.clangd

CompileFlags:
  Add: [-Wno-unknown-warning-option, -mmcu=avr128db48]
  Remove: [-m*, -f*]

compile_commands.json

[
{
  "directory": "/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/build",
  "command": "/Users/aasmundnorsett/Library/avr-toolchain/bin/avr-gcc -DF_CPU=3333333 -DNDEBUG -D__AVR_DEV_LIB_NAME__=avr128db48 -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/include -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src -O3 -DNDEBUG -std=gnu11 -mmcu=avr128db48 -Werror -Wall -Wextra -Wpedantic -Wshadow -Wno-array-bounds -Wno-vla -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -ffunction-sections -fdata-sections -fno-split-wide-types -fno-tree-scev-cprop -Os -I/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/device_pack/include -B/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/device_pack/gcc/dev/avr128db48 -o CMakeFiles/lab4.dir/src/main.c.obj -c /Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c",
  "file": "/Users/aasmundnorsett/Documents/NTNU/Semester7/low-level-programming/labs/lab-4/src/main.c",
  "output": "CMakeFiles/lab4.dir/src/main.c.obj"
}
]

System information

Output of clangd --version:

clangd version 19.1.0 (https://github.com/llvm/llvm-project a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)
Features: mac+grpc+xpc
Platform: arm64-apple-darwin23.6.0; target=x86_64-apple-darwin23.6.0

Editor/LSP plugin:

Neovim v0.10.2
Neovim built in lsp-plugin

Operating system:
Apple M1, MacOS version Sonoma 14.7
Also tested same setup on Ubuntu desktop 24.04.1

[AasmundN]

It seems to me like this might be an issue with clang itself? avr128db48 does not seem to be supported:

[HighCommander4]

The "invalid AST" error is downstream of error: unknown target CPU 'avr128db48'.

As you observe, clang does not support this exact target.

But for code editing purposes, a similar one that it does support may be good enough. What happens if you omit -mmcu=avr128db48 from your .clangd file, or substitute a different CPU which is in the supported list?

[AasmundN]

As a temporary solution I removed the -mmcu flag from .clangd, like you suggest, and include the header directly

#define _AVR_IO_H_
#include <avr/ioavr128db48.h>

Very ugly.

[AasmundN]

After doing some more digging, with your suggestion in mind @HighCommander4, I was able to find something that works ok. I looked through the llvm-project repo and found the following in the file /llvm/lib/Target/AVR/AVRDevices.td:

// Generic MCUs
// Note that several versions of GCC has strange ELF architecture
// settings for backwards compatibility - see `gas/config/tc-avr.c`
// in AVR binutils. We do not replicate this.
def : Device<"avr1", FamilyAVR1, ELFArchAVR1>;
def : Device<"avr2", FamilyAVR2, ELFArchAVR2>;
def : Device<"avr25", FamilyAVR25, ELFArchAVR25>;
def : Device<"avr3", FamilyAVR3, ELFArchAVR3>;
def : Device<"avr31", FamilyAVR31, ELFArchAVR31>;
def : Device<"avr35", FamilyAVR35, ELFArchAVR35>;
def : Device<"avr4", FamilyAVR4, ELFArchAVR4>;
def : Device<"avr5", FamilyAVR5, ELFArchAVR5>;
def : Device<"avr51", FamilyAVR51, ELFArchAVR51>;
def : Device<"avr6", FamilyAVR6, ELFArchAVR6>;
def : Device<"avrxmega1", FamilyXMEGA, ELFArchXMEGA1>;
def : Device<"avrxmega2", FamilyXMEGA, ELFArchXMEGA2>;
def : Device<"avrxmega3", FamilyXMEGA3, ELFArchXMEGA3>;
def : Device<"avrxmega4", FamilyXMEGA, ELFArchXMEGA4>;
def : Device<"avrxmega5", FamilyXMEGA, ELFArchXMEGA5>;
def : Device<"avrxmega6", FamilyXMEGA, ELFArchXMEGA6>;
def : Device<"avrxmega7", FamilyXMEGA, ELFArchXMEGA7>;
def : Device<"avrtiny", FamilyTiny, ELFArchTiny>;

I am not sure which of these device families is the closest to the avr-dx family, but I tested with avrxmega4 because the /gcc/dev/avr128db48 folder in the device family pack includes a folder named avrxmega4. So I guess they relate to each other in some way (?). My new .clangd file looks like this:

CompileFlags:
  Add: [-Wno-unknown-warning-option, -Wno-c23-extensions, -mmcu=avrxmega4, -D__AVR_XMEGA__=1]
  Remove: [-m*, -f*]

With these modifications to the setup (keeping everything else the same) the LSP is no longer angry and it findes the correct header file ioavr128db48.h.

[tomtor]

llvm/llvm-project#144229

So this issue can be closed? Note that one still needs to install a recent AVR library with the newer crt files.

[AasmundN]

Probably, I will test this out and see.