in kernel/sim-console.c [14:23]
static void sim_write(struct console *con, const char *s, unsigned n)
{
register const char *_ptr __asm__("er1") = s;
register const unsigned _len __asm__("er2") = n;
__asm__("sub.l er0,er0\n\t" /* er0 = 1 (stdout) */
"inc.l #1,er0\n\t"
".byte 0x5e,0x00,0x00,0xc7\n\t" /* jsr @0xc7 (sys_write) */
: : "g"(_ptr), "g"(_len):"er0");
}