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author | Marc Zyngier <Marc.Zyngier@arm.com> | 2013-02-27 19:06:00 +0100 |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2013-03-20 17:46:42 +0100 |
commit | 0492f72508184d451101564e235b0c32edf9acd3 (patch) | |
tree | b14e17c7985fdf92bfb31092fa2c28cbcde8d20a | |
parent | arm64: add read_cpuid_{implementor,part_number,mpidr} (diff) | |
download | linux-0492f72508184d451101564e235b0c32edf9acd3.tar.xz linux-0492f72508184d451101564e235b0c32edf9acd3.zip |
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 <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r-- | arch/arm64/kernel/early_printk.c | 12 |
1 files changed, 12 insertions, 0 deletions
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, }, {} }; |