From patchwork Tue Oct 9 14:20:47 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [20/20] powerpc/xmon: Fallback to printk() in xmon_printf() if udbg is not setup Date: Tue, 09 Oct 2012 04:20:47 -0000 From: Michael Ellerman X-Patchwork-Id: 190333 Message-Id: <1349792447-15714-20-git-send-email-michael@ellerman.id.au> To: Cc: Paul Mackerras , Anton Blanchard 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 --- arch/powerpc/xmon/nonstdio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c index 942d0f6..bce3dcf 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)