diff options
Diffstat (limited to 'src/pkg/runtime/runtime.h')
| -rw-r--r-- | src/pkg/runtime/runtime.h | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h index 88e516139..c9b6a2611 100644 --- a/src/pkg/runtime/runtime.h +++ b/src/pkg/runtime/runtime.h @@ -64,10 +64,22 @@ typedef struct hash Hmap; typedef struct Hchan Hchan; /* - * per cpu declaration + * per-cpu declaration. + * "extern register" is a special storage class implemented by 6c, 8c, etc. + * on machines with lots of registers, it allocates a register that will not be + * used in generated code. on the x86, it allocates a slot indexed by a + * segment register. + * + * amd64: allocated downwards from R15 + * x86: allocated upwards from 0(FS) + * arm: allocated upwards from R9 + * + * every C file linked into a Go program must include runtime.h + * so that the C compiler knows to avoid other uses of these registers. + * the Go compilers know to avoid them. */ -extern register G* g; // R15 -extern register M* m; // R14 +extern register G* g; +extern register M* m; /* * defined constants |