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 <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: David Cohen <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stuart R. Anderson <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Cleaned it up a bit. ]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions