From 0492f72508184d451101564e235b0c32edf9acd3 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 27 Feb 2013 18:06:00 +0000 Subject: [PATCH] arm64: early_printk: add support for FastModel console output Enable early_printk to use the FastModel semihosting to output the early kernel messages. Works both for host and guest kernels. To use this feature, pass "early_printk=smh" to the kernel. Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas --- arch/arm64/kernel/early_printk.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/kernel/early_printk.c b/arch/arm64/kernel/early_printk.c index 7e320a2edb9b..0bb7436c57dc 100644 --- a/arch/arm64/kernel/early_printk.c +++ b/arch/arm64/kernel/early_printk.c @@ -40,6 +40,17 @@ static void pl011_printch(char ch) ; } +/* + * Semihosting-based debug console + */ +static void smh_printch(char ch) +{ + asm volatile("mov x1, %0\n" + "mov x0, #3\n" + "hlt 0xf000\n" + : : "r" (&ch) : "x0", "x1", "memory"); +} + struct earlycon_match { const char *name; void (*printch)(char ch); @@ -47,6 +58,7 @@ struct earlycon_match { static const struct earlycon_match earlycon_match[] __initconst = { { .name = "pl011", .printch = pl011_printch, }, + { .name = "smh", .printch = smh_printch, }, {} }; -- 2.20.1