On 2/7/24 08:20, del...@kernel.org wrote:
@@ -484,3 +486,33 @@ uint64_t HELPER(hshradd)(uint64_t r1, uint64_t r2,
uint32_t sh)
}
return ret;
}
+
+/*
+ * diag_console_output() is a helper function used during the initial bootup
+ * process of the SeaBIOS-hppa firmware. During the bootup phase, addresses of
+ * serial ports on e.g. PCI busses are unknown and most other devices haven't
+ * been initialized and configured yet. With help of a simple "diag" assembler
+ * instruction and an ASCII character code in register %r26 firmware can easily
+ * print debug output without any dependencies to the first serial port and use
+ * that as serial console.
+ */
+void HELPER(diag_console_output)(CPUHPPAState *env)
+{
+ CharBackend *serial_backend;
+ Chardev *serial_port;
+ unsigned char c;
+
+ /* find first serial port */
+ serial_port = serial_hd(0);
+ if (!serial_port)
+ return;
+
+ /* get serial_backend for the serial port */
+ serial_backend = serial_port->be;
+ if (!serial_backend ||
+ !qemu_chr_fe_backend_connected(serial_backend))
+ return;
+
+ c = (unsigned char)env->gr[26];
+ qemu_chr_fe_write(serial_backend, &c, sizeof(c));
+}
Looks like this should go in sys_helper.c instead.
Missing ifdefs break hppa-linux-user?
Also, missing braces.
r~
