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| author | Julien Grall <julien.grall@linaro.org> | 2013-05-23 15:50:11 +0100 |
|---|---|---|
| committer | Ian Campbell <ian.campbell@citrix.com> | 2013-05-30 09:14:48 +0100 |
| commit | cafdceb66e154f1ac204be935f9030959827bd1f (patch) | |
| tree | 99e3b01483853eb6fda2461ca72cdaf1093fd13d | |
| parent | 121dac93afd2f600485618d9b493892e2fca8fa8 (diff) | |
| download | xen-cafdceb66e154f1ac204be935f9030959827bd1f.tar.gz xen-cafdceb66e154f1ac204be935f9030959827bd1f.tar.bz2 xen-cafdceb66e154f1ac204be935f9030959827bd1f.zip | |
xen/arm: avoid lost characters with early_printk
Introduce the function early_flush to wait until the UART has finished to
transfer the character.
When early printk is enabled, it's possible to loose the last characters if:
- the UART is initialized by the UART driver
- Xen hang
This is result to a truncated message. To be sure that the message is fully
transfered by early_printk, add a call to early_flush. This will avoid lost
characters.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
| -rw-r--r-- | xen/arch/arm/arm32/debug.S | 7 | ||||
| -rw-r--r-- | xen/arch/arm/arm64/debug.S | 7 | ||||
| -rw-r--r-- | xen/arch/arm/early_printk.c | 7 |
3 files changed, 21 insertions, 0 deletions
diff --git a/xen/arch/arm/arm32/debug.S b/xen/arch/arm/arm32/debug.S index 1bfbfc1968..92f572499d 100644 --- a/xen/arch/arm/arm32/debug.S +++ b/xen/arch/arm/arm32/debug.S @@ -32,6 +32,13 @@ early_putch: early_uart_transmit r1, r0 mov pc, lr +.globl early_flush +/* Flush the UART - this function is called by C */ +early_flush: + ldr r1, =FIXMAP_ADDR(FIXMAP_CONSOLE) /* r1 := VA UART base address */ + early_uart_ready r1, r2 + mov pc, lr + /* * Local variables: * mode: ASM diff --git a/xen/arch/arm/arm64/debug.S b/xen/arch/arm/arm64/debug.S index 38b7c74ff7..c7b5e6ceea 100644 --- a/xen/arch/arm/arm64/debug.S +++ b/xen/arch/arm/arm64/debug.S @@ -32,6 +32,13 @@ early_putch: early_uart_transmit x15, w0 ret +.globl early_flush +/* Flush the UART - this function is called by C */ +early_flush: + ldr x15, =FIXMAP_ADDR(FIXMAP_CONSOLE) /* x15 := VA UART base address */ + early_uart_ready x15, 1 + ret + /* * Local variables: * mode: ASM diff --git a/xen/arch/arm/early_printk.c b/xen/arch/arm/early_printk.c index 59503231ec..ca151a5b21 100644 --- a/xen/arch/arm/early_printk.c +++ b/xen/arch/arm/early_printk.c @@ -16,6 +16,7 @@ #include <asm/early_printk.h> void early_putch(char c); +void early_flush(void); /* Early printk buffer */ static char __initdata buf[512]; @@ -34,6 +35,12 @@ static void __init early_vprintk(const char *fmt, va_list args) { vsnprintf(buf, sizeof(buf), fmt, args); early_puts(buf); + + /* + * Wait the UART has finished to transfer all characters before + * to continue. This will avoid lost characters if Xen abort. + */ + early_flush(); } void __init early_printk(const char *fmt, ...) |