cross-gcc

Name: cross-gcc
Author: mohitmishra786

376installs19forks

How to install cross-gcc?

mohitmishra786/low-level-dev-skills/cross-gcc

$npx -y skills add mohitmishra786/low-level-dev-skills --skill cross-gcc

Installs into the current project.

Summary

Cross-compilation with GCC skill for embedded and multi-architecture targets. Use when setting up cross-gcc toolchains, configuring sysroots, building for ARM/AArch64/RISC-V/MIPS from an x86-64 host, troubleshooting wrong-architecture errors, or running cross-compiled binaries un

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SKILL.md

1	# Cross-GCC
2
3	## Purpose
4
5	Guide agents through setting up and using cross-compilation GCC toolchains: triplets, sysroots, pkg-config, QEMU-based testing, and common failure modes.
6
7	## Triggers
8
9	- "How do I compile for ARM on my x86 machine?"
10	- "I'm getting 'wrong ELF class' or 'cannot execute binary file'"
11	- "How do I set up a sysroot for cross-compilation?"
12	- "pkg-config returns host libraries in my cross build"
13	- "How do I debug a cross-compiled binary with QEMU + GDB?"
14
15	## Workflow
16
17	### 1. Understand the triplet
18
19	A GNU triplet has the form `<arch>-<vendor>-<os>-<abi>` (often 3 or 4 parts):
20
21	\| Triplet \| Target \|
22	\|---------\|--------\|
23	\| `aarch64-linux-gnu` \| 64-bit ARM Linux (glibc) \|
24	\| `arm-linux-gnueabihf` \| 32-bit ARM Linux hard-float \|
25	\| `arm-none-eabi` \| Bare-metal ARM (no OS) \|
26	\| `riscv64-linux-gnu` \| 64-bit RISC-V Linux \|
27	\| `x86_64-w64-mingw32` \| Windows (MinGW) from Linux \|
28	\| `mipsel-linux-gnu` \| Little-endian MIPS Linux \|
29
30	### 2. Install the toolchain
31
32	```bash
33	# Debian/Ubuntu
34	sudo apt install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu
35
36	# For bare-metal ARM (Cortex-M)
37	sudo apt install gcc-arm-none-eabi binutils-arm-none-eabi
38
39	# Verify
40	aarch64-linux-gnu-gcc --version
41	```
42
43	### 3. Basic cross-compilation
44
45	```bash
46	# C
47	aarch64-linux-gnu-gcc -O2 -o hello hello.c
48
49	# C++
50	aarch64-linux-gnu-g++ -O2 -std=c++17 -o hello hello.cpp
51
52	# Bare-metal (no stdlib, no OS)
53	arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 \
54	-ffreestanding -nostdlib -T linker.ld -o firmware.elf startup.s main.c
55	```
56
57	### 4. Sysroot
58
59	A sysroot is a directory containing the target's headers and libraries. Required when your code links against target-specific libraries.
60
61	```bash
62	# Use a sysroot
63	aarch64-linux-gnu-gcc --sysroot=/path/to/aarch64-sysroot -O2 -o prog main.c
64
65	# Common sysroot sources:
66	# - Raspberry Pi: download from raspbian/raspios
67	# - Debian multiarch: debootstrap --arch arm64 bullseye /tmp/sysroot
68	# - Yocto/Buildroot: generated automatically in build output
69	```
70
71	Verify the sysroot is correct:
72
73	```bash
74	aarch64-linux-gnu-gcc --sysroot=/path/to/sysroot -v -E - < /dev/null 2>&1 \| grep sysroot
75	```
76
77	### 5. pkg-config for cross builds
78
79	`pkg-config` will return host library paths by default. Override:
80
81	```bash
82	export PKG_CONFIG_SYSROOT_DIR=/path/to/sysroot
83	export PKG_CONFIG_LIBDIR=${PKG_CONFIG_SYSROOT_DIR}/usr/lib/aarch64-linux-gnu/pkgconfig:${PKG_CONFIG_SYSROOT_DIR}/usr/share/pkgconfig
84	export PKG_CONFIG_PATH= # clear host path
85
86	pkg-config --libs libssl # now returns target paths
87	```
88
89	### 6. CMake cross-compilation
90
91	Create a toolchain file `aarch64.cmake`:
92
93	```cmake
94	set(CMAKE_SYSTEM_NAME Linux)
95	set(CMAKE_SYSTEM_PROCESSOR aarch64)
96
97	set(CMAKE_C_COMPILER aarch64-linux-gnu-gcc)
98	set(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)
99
100	set(CMAKE_SYSROOT /path/to/aarch64-sysroot)
101	set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
102	set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
103	set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
104	```
105
106	```bash
107	cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=aarch64.cmake
108	cmake --build build
109	```
110
111	### 7. Test with QEMU
112
113	```bash
114	# User-mode emulation (Linux binaries, no full OS)
115	sudo apt install qemu-user-static
116
117	qemu-aarch64-static ./hello
118	# Or set binfmt_misc for transparent execution:
119	# Then just: ./hello
120
121	# GDB remote debug via QEMU
122	qemu-aarch64-static -g 1234 ./hello &
123	aarch64-linux-gnu-gdb -ex "target remote :1234" ./hello
124	```
125
126	### 8. Common errors
127
128	\| Error \| Cause \| Fix \|
129	\|-------\|-------\|-----\|
130	\| `cannot execute binary file: Exec format error` \| Running target binary on host without QEMU \| Use `qemu-<arch>-static` \|
131	\| `wrong ELF class: ELFCLASS64` (or 32) \| Wrong-architecture object linked \| Check triplet; ensure all objects use same toolchain \|
132	\| `/usr/bin/ld: cannot find -lfoo` \| Host library path used for cross-link \| Set `--sysroot`; fix `PKG_CONFIG_LIBDIR` \|
133	\| `undefined reference to '__aeabi_*'` \| Missing ARM ABI runtime \| Link with `-lgcc` or `-lclang_rt.builtins` \|
134	\| `relocation R_AARCH64_ADR_PREL_PG_HI21 out of range` \| Distance too large \| Use `-mcmodel=large` or restructure \|
135	\| `unrecognized opcode` \| Wrong `-mcpu` or `-march` \| Set correct CPU flags for target \|
136
137	### 9. Environment variables
138
139	```bash
140	# Tell build systems to use cross-compiler
141	export CC=aarch64-linux-gnu-gcc
142	export CXX=aarch64-linux-gnu-g++
143	export AR=aarch64-linux-gnu-ar
144	export STRIP=aarch64-linux-gnu-strip
145	export OBJDUMP=aarch64-linux-gnu-objdump
146
147	# For autoconf projects
148	./configure --host=aarch64-linux-gnu --prefix=/usr
149	```
150
151	For a refe

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cross-gcc

376installs19forks

View on GitHub

How to install cross-gcc?

mohitmishra786/low-level-dev-skills/cross-gcc

$npx -y skills add mohitmishra786/low-level-dev-skills --skill cross-gcc

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Cross-GCC
2
3	## Purpose
4
5	Guide agents through setting up and using cross-compilation GCC toolchains: triplets, sysroots, pkg-config, QEMU-based testing, and common failure modes.
6
7	## Triggers
8
9	- "How do I compile for ARM on my x86 machine?"
10	- "I'm getting 'wrong ELF class' or 'cannot execute binary file'"
11	- "How do I set up a sysroot for cross-compilation?"
12	- "pkg-config returns host libraries in my cross build"
13	- "How do I debug a cross-compiled binary with QEMU + GDB?"
14
15	## Workflow
16
17	### 1. Understand the triplet
18
19	A GNU triplet has the form `<arch>-<vendor>-<os>-<abi>` (often 3 or 4 parts):
20
21	\| Triplet \| Target \|
22	\|---------\|--------\|
23	\| `aarch64-linux-gnu` \| 64-bit ARM Linux (glibc) \|
24	\| `arm-linux-gnueabihf` \| 32-bit ARM Linux hard-float \|
25	\| `arm-none-eabi` \| Bare-metal ARM (no OS) \|
26	\| `riscv64-linux-gnu` \| 64-bit RISC-V Linux \|
27	\| `x86_64-w64-mingw32` \| Windows (MinGW) from Linux \|
28	\| `mipsel-linux-gnu` \| Little-endian MIPS Linux \|
29
30	### 2. Install the toolchain
31
32	```bash
33	# Debian/Ubuntu
34	sudo apt install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu
35
36	# For bare-metal ARM (Cortex-M)
37	sudo apt install gcc-arm-none-eabi binutils-arm-none-eabi
38
39	# Verify
40	aarch64-linux-gnu-gcc --version
41	```
42
43	### 3. Basic cross-compilation
44
45	```bash
46	# C
47	aarch64-linux-gnu-gcc -O2 -o hello hello.c
48
49	# C++
50	aarch64-linux-gnu-g++ -O2 -std=c++17 -o hello hello.cpp
51
52	# Bare-metal (no stdlib, no OS)
53	arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 \
54	-ffreestanding -nostdlib -T linker.ld -o firmware.elf startup.s main.c
55	```
56
57	### 4. Sysroot
58
59	A sysroot is a directory containing the target's headers and libraries. Required when your code links against target-specific libraries.
60
61	```bash
62	# Use a sysroot
63	aarch64-linux-gnu-gcc --sysroot=/path/to/aarch64-sysroot -O2 -o prog main.c
64
65	# Common sysroot sources:
66	# - Raspberry Pi: download from raspbian/raspios
67	# - Debian multiarch: debootstrap --arch arm64 bullseye /tmp/sysroot
68	# - Yocto/Buildroot: generated automatically in build output
69	```
70
71	Verify the sysroot is correct:
72
73	```bash
74	aarch64-linux-gnu-gcc --sysroot=/path/to/sysroot -v -E - < /dev/null 2>&1 \| grep sysroot
75	```
76
77	### 5. pkg-config for cross builds
78
79	`pkg-config` will return host library paths by default. Override:
80
81	```bash
82	export PKG_CONFIG_SYSROOT_DIR=/path/to/sysroot
83	export PKG_CONFIG_LIBDIR=${PKG_CONFIG_SYSROOT_DIR}/usr/lib/aarch64-linux-gnu/pkgconfig:${PKG_CONFIG_SYSROOT_DIR}/usr/share/pkgconfig
84	export PKG_CONFIG_PATH= # clear host path
85
86	pkg-config --libs libssl # now returns target paths
87	```
88
89	### 6. CMake cross-compilation
90
91	Create a toolchain file `aarch64.cmake`:
92
93	```cmake
94	set(CMAKE_SYSTEM_NAME Linux)
95	set(CMAKE_SYSTEM_PROCESSOR aarch64)
96
97	set(CMAKE_C_COMPILER aarch64-linux-gnu-gcc)
98	set(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)
99
100	set(CMAKE_SYSROOT /path/to/aarch64-sysroot)
101	set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
102	set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
103	set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
104	```
105
106	```bash
107	cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=aarch64.cmake
108	cmake --build build
109	```
110
111	### 7. Test with QEMU
112
113	```bash
114	# User-mode emulation (Linux binaries, no full OS)
115	sudo apt install qemu-user-static
116
117	qemu-aarch64-static ./hello
118	# Or set binfmt_misc for transparent execution:
119	# Then just: ./hello
120
121	# GDB remote debug via QEMU
122	qemu-aarch64-static -g 1234 ./hello &
123	aarch64-linux-gnu-gdb -ex "target remote :1234" ./hello
124	```
125
126	### 8. Common errors
127
128	\| Error \| Cause \| Fix \|
129	\|-------\|-------\|-----\|
130	\| `cannot execute binary file: Exec format error` \| Running target binary on host without QEMU \| Use `qemu-<arch>-static` \|
131	\| `wrong ELF class: ELFCLASS64` (or 32) \| Wrong-architecture object linked \| Check triplet; ensure all objects use same toolchain \|
132	\| `/usr/bin/ld: cannot find -lfoo` \| Host library path used for cross-link \| Set `--sysroot`; fix `PKG_CONFIG_LIBDIR` \|
133	\| `undefined reference to '__aeabi_*'` \| Missing ARM ABI runtime \| Link with `-lgcc` or `-lclang_rt.builtins` \|
134	\| `relocation R_AARCH64_ADR_PREL_PG_HI21 out of range` \| Distance too large \| Use `-mcmodel=large` or restructure \|
135	\| `unrecognized opcode` \| Wrong `-mcpu` or `-march` \| Set correct CPU flags for target \|
136
137	### 9. Environment variables
138
139	```bash
140	# Tell build systems to use cross-compiler
141	export CC=aarch64-linux-gnu-gcc
142	export CXX=aarch64-linux-gnu-g++
143	export AR=aarch64-linux-gnu-ar
144	export STRIP=aarch64-linux-gnu-strip
145	export OBJDUMP=aarch64-linux-gnu-objdump
146
147	# For autoconf projects
148	./configure --host=aarch64-linux-gnu --prefix=/usr
149	```
150
151	For a refe

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