I'm implementing cross-compilation support in rules_go <https://github.com/bazelbuild/rules_go>. This takes a low-level approach to building golang targets that involves use of the individual toolchain components such as 'go tool asm', 'go tool compile', 'go tool link', etc...
Cross-compilation of pure-go inputs is working swimmingly. However, I'm wondering how to cross-compile assembly inputs correctly. Consider the following assembly file that defines an 'add' method. *#include "textflag.h"* *TEXT ·add(SB),NOSPLIT,$0* * MOVQ x+0(FP), BX* * MOVQ y+8(FP), BP* * ADDQ BP, BX* * MOVQ BX, ret+16(FP)* * RET* For example, this works: *$ go tool asm -I $(go env GOROOT)/pkg/include -o add.o add.s* *$ hexdump add.o* *0000000 67 6f 20 6f 62 6a 65 63 74 20 64 61 72 77 69 6e* *0000010 20 61 6d 64 36 34 20 67 6f 31 2e 36 2e 32 0a 21* *0000020 0a 00 00 67 6f 31 33 6c 64 01 00 fe 02 0c 22 22* *0000030 2e 61 64 64 00 00 40 00 00 40 48 8b 5c 24 08 48* *0000040 8b 6c 24 10 48 01 eb 48 89 5c 24 18 c3 cc cc cc* *0000050 cc cc cc cc cc cc cc cc cc cc 00 ff ff ff ff 0f* *0000060 00 02 00 00 06 02 20 00 06 02 20 00 16 0a 05 02* *0000070 05 02 03 02 05 02 0e 00 00 02 28 22 22 2e 61 64* *0000080 64 2e 61 72 67 73 5f 73 74 61 63 6b 6d 61 70 00* *0000090 00 02 52 2f 55 73 65 72 73 2f 70 63 6a 2f 67 69* *00000a0 74 68 75 62 2f 67 72 70 63 2d 67 72 65 65 74 65* *00000b0 72 74 69 6d 65 72 2f 61 64 64 2e 73 02 ff ff 67* *00000c0 6f 31 33 6c 64 * *00000c5* Given the magic of "goose" and "garch" (and it is magical), I expected this to work: *$ env GOOS=linux GOARCH=arm go tool asm -I $(go env GOROOT)/pkg/include -o add.o add.s* *add.s:4: unrecognized instruction "MOVQ"* *add.s:5: unrecognized instruction "MOVQ"* *add.s:6: unrecognized instruction "ADDQ"* *add.s:7: unrecognized instruction "MOVQ"* *asm: asm: assembly of add.s failed* This was the initial issue for this post. However, I figured that part out (the std library needs to be compiled first). So this works: *$ env GOOS=linux GOARCH=arm go install std && go tool asm -I $(go env GOROOT)/pkg/include -o add.o add.s* However, now I'm curious why whatever platform GOOS_GOARCH I choose, the file is exactly the same (see hexdump above). So i'm wondering why that is. Am I doing something wrong? If not, why are GOOS and GOARCH needed at all at this stage? Thanks for helping me clear this up, and thanks for golang! Paul -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
