From 3a51b2a2c3cedc0d2a9ce981b8e00ab8cefcb6b7 Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Thu, 15 Oct 2020 13:25:14 +0900 Subject: arch: arm/xen: add putc() for debugging This new function, xen_debug_putc(), is intended to be used to enable CONFIG_DEBUG_UART on xen guest. Please note that the underlying functionality in Xen is available only when Xen is configured with !NDEBUG but is much simpler than a generic HYPERVISOR_console_io(). Signed-off-by: AKASHI Takahiro Reviewed-by: Peng Fan --- arch/arm/include/asm/xen/hypercall.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch') diff --git a/arch/arm/include/asm/xen/hypercall.h b/arch/arm/include/asm/xen/hypercall.h index a4fd077079..121ccfcc60 100644 --- a/arch/arm/include/asm/xen/hypercall.h +++ b/arch/arm/include/asm/xen/hypercall.h @@ -19,4 +19,10 @@ int HYPERVISOR_sched_op(int cmd, void *arg); int HYPERVISOR_event_channel_op(int cmd, void *arg); unsigned long HYPERVISOR_hvm_op(int op, void *arg); int HYPERVISOR_memory_op(unsigned int cmd, void *arg); + +static inline void xen_debug_putc(int c) +{ + register int v __asm__ ("x0") = c; + __asm__ __volatile__("hvc 0xfffe" : "=r" (v) : "0" (v)); +} #endif /* _ASM_ARM_XEN_HYPERCALL_H */ -- cgit v1.2.3