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Commit 0492f725 authored by Marc Zyngier's avatar Marc Zyngier Committed by Catalin Marinas
Browse files

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: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent d9c1951f

arch/arm64/kernel/early_printk.c

+12 −0
Original line number Diff line number Diff line
@@ -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, },

	{}

};