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authorSteven Rostedt <rostedt@goodmis.org>2015-07-06 10:14:34 -0400
committerIngo Molnar <mingo@kernel.org>2015-07-06 17:33:47 +0200
commit827a82ff399523a954253dfea401af748640f0f4 (patch)
tree73fd156b632ebb81953ee5b0d5edb964eadfac0d /arch/x86
parent20d5e4a9cd453991e2590a4c25230a99b42dee0c (diff)
downloadlinux-827a82ff399523a954253dfea401af748640f0f4.tar.bz2
x86/earlyprintk: Allow early_printk() to use console style parameters like '115200n8'
When I enable early_printk on a kernel, I cut and paste the console= input and add to earlyprintk parameter. But I notice recently that ktest has not been detecting triple faults. The way it detects it, is by seeing the kernel banner "Linux version .." with a different kernel version pop up. Then I noticed that early printk was no longer working on my console, which was why ktest was not seeing it. I bisected it down and it was added to 4.0 with this commit: ea9e9d802902 ("Specify PCI based UART for earlyprintk") because it converted the simple_strtoul() that converts the baud number into a kstrtoul(). The problem with this is, I had as my baud rate, 115200n8 (acceptable for console=ttyS0), but because of the "n8", the kstrtoul() doesn't parse the baud rate and returns an error, which sets the baud rate to the default 9600. This explains the garbage on my screen. Now, earlyprintk= kernel parameter does not say it accepts that format. Thus, one answer would simply be me changing my kernel parameters to remove the "n8" since it isn't parsed anyway. But I wonder if other people run into this, and it seems strange that the two consoles for serial accepts different input. I could also extend this to have earlyprintk do something with that "n8" or whatever it has and have it match the console parsing (which, BTW, still uses simple_strtoul(), as I guess it has to). This patch just makes my old kernel parameter parsing work like it use to. Although, simple_strtoull() is considered obsolete, it is the only standard string parsing function that parses a number that is attached to text. Ironically, commit ea9e9d802902 also added several calls to simple_strtoul()! Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Alan Cox <alan@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Cohen <david.a.cohen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stuart R. Anderson <stuart.r.anderson@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150706101434.5f6a351b@gandalf.local.home [ Cleaned it up a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/early_printk.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 89427d8d4fc5..eec40f595ab9 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -175,7 +175,9 @@ static __init void early_serial_init(char *s)
}
if (*s) {
- if (kstrtoul(s, 0, &baud) < 0 || baud == 0)
+ baud = simple_strtoull(s, &e, 0);
+
+ if (baud == 0 || s == e)
baud = DEFAULT_BAUD;
}