nodejs/node · error

CPU architecture "%s" is unknown.\n

Error message

CPU architecture "%s" is unknown.\n

What it means

When -o/--object and -c/--cpu-arch are both in use, genccode calls checkCpuArchitecture() on the -c value. The accepted values are exactly x64, x86, arm64, arm (case-insensitive pairs). Any other string is rejected with this message and the tool returns -1 before generating object code.

Source

Thrown at deps/icu-small/source/tools/genccode/genccode.c:202

                writeCCode(filename, options[kOptDestDir].value,
                           options[kOptEntryPoint].doesOccur ? options[kOptEntryPoint].value : NULL,
                           options[kOptName].doesOccur ? options[kOptName].value : NULL,
                           options[kOptFilename].doesOccur ? options[kOptFilename].value : NULL,
                           NULL,
                           0);
                break;
            case CALL_WRITEASSEMBLY:
                writeAssemblyCode(filename, options[kOptDestDir].value,
                                  options[kOptEntryPoint].doesOccur ? options[kOptEntryPoint].value : NULL,
                                  options[kOptFilename].doesOccur ? options[kOptFilename].value : NULL,
                                  NULL,
                                  0);
                break;
#ifdef CAN_GENERATE_OBJECTS
            case CALL_WRITEOBJECT:
                if(options[kOptCpuArch].doesOccur) {
                    if (!checkCpuArchitecture(options[kOptCpuArch].value)) {
                        fprintf(stderr,
                            "CPU architecture \"%s\" is unknown.\n", options[kOptCpuArch].value);
                        return -1;
                    }
                }
                writeObjectCode(filename, options[kOptDestDir].value,
                                options[kOptEntryPoint].doesOccur ? options[kOptEntryPoint].value : NULL,
                                options[kOptMatchArch].doesOccur ? options[kOptMatchArch].value : NULL,
                                options[kOptCpuArch].doesOccur ? options[kOptCpuArch].value : NULL,
                                options[kOptFilename].doesOccur ? options[kOptFilename].value : NULL,
                                NULL,
                                0,
                                !options[kOptSkipDllExport].doesOccur);
                break;
#endif
            default:
                /* Should never occur. */
                break;
            }

View on GitHub (pinned to 1b2de5e052)

Solutions

1. Map your architecture to genccode's name: aarch64->arm64, amd64->x64, i386/i686->x86, armhf/armv7->arm.
2. Drop -c if you do not need object generation with a specific arch (genccode will infer the host arch).
3. Verify the spelling is exactly one of x64/x86/arm64/arm (case-insensitive).

Example fix

# before
genccode -o -c aarch64 data.dat

# after
genccode -o -c arm64 data.dat

// normalize host arch names to genccode's accepted set
ALIAS = {'aarch64':'arm64','amd64':'x64','x86_64':'x64','i386':'x86','i686':'x86','armhf':'arm','armv7l':'arm'}
cpu = ALIAS.get(host_arch.lower(), host_arch.lower())
if cpu not in {'x64','x86','arm64','arm'}:
    raise ValueError(f'unsupported --cpu-arch {host_arch}; map to x64/x86/arm64/arm')

// type guard for genccode cpu-arch values
bool is_valid_cpu_arch(const char* a) {
    return strcmp(a,"x64")==0||strcmp(a,"x86")==0||strcmp(a,"arm64")==0||strcmp(a,"arm")==0;
}

When it happens

Trigger: options[kOptCpuArch].value is not one of {x64,x86,arm64,arm,X64,X86,ARM64,ARM}. Common misses: "aarch64" (use "arm64"), "amd64" (use "x64"), "i386"/"i686" (use "x86"), "armhf" (use "arm").

Common situations: Cross-compile scripts that pass the GNU triple's machine name (aarch64, amd64) instead of genccode's normalized names; CI matrices using architecture labels from a different vocabulary than ICU's; copying -c from a clang/gcc -march flag.

Related errors

• error in command line argument "%s"\n
• Assembly type "%s" is unknown.\n
• U_FILE_ACCESS_ERROR
• U_ILLEGAL_ARGUMENT_ERROR
• U_UNSUPPORTED_ERROR

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/c142305d80a042b8. Report an issue: GitHub.