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authorMichael Ellerman <michael@ellerman.id.au>2012-10-09 04:20:47 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-11-15 13:00:02 +1100
commitb2bb65f680a7b2faa5d6332c02752dca83a49cd6 (patch)
tree7aa08b554b4e9c265d54a955c3ea610339bcd276
parent0104cd6839bd575f0aa1af4125eb865dc0391aae (diff)
downloadlinaro-lsk-b2bb65f680a7b2faa5d6332c02752dca83a49cd6.tar.gz
powerpc/xmon: Fallback to printk() in xmon_printf() if udbg is not setup
It is possible to configure a kernel which has xmon enabled, but has no udbg backend to provide IO. This can make xmon rather confusing, as it produces no output, blocks for two seconds, and then returns. As a last resort we can instead try to printk(), which may deadlock or otherwise crash, but tries quite hard not to. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/xmon/nonstdio.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c
index 942d0f6b187..bce3dcfe505 100644
--- a/arch/powerpc/xmon/nonstdio.c
+++ b/arch/powerpc/xmon/nonstdio.c
@@ -111,13 +111,19 @@ char *xmon_gets(char *str, int nb)
void xmon_printf(const char *format, ...)
{
va_list args;
- int n;
static char xmon_outbuf[1024];
+ int rc, n;
va_start(args, format);
n = vsnprintf(xmon_outbuf, sizeof(xmon_outbuf), format, args);
va_end(args);
- xmon_write(xmon_outbuf, n);
+
+ rc = xmon_write(xmon_outbuf, n);
+
+ if (n && rc == 0) {
+ /* No udbg hooks, fallback to printk() - dangerous */
+ printk(xmon_outbuf);
+ }
}
void xmon_puts(const char *str)