Re: [PATCH v3] printk: Have printk() never buffer its data

Kay Sievers
2012-07-06T00:56:41Z

On Fri, Jul 6, 2012 at 2:41 AM, Michael Neuling <mikey@neuling.org> wrote:

>> > Does this happen only very early during bootup, or also later when the
>> > box fully initialized?
>
> I'm seeing during boot but not later (xmon (ppc kernel debugger) doesn't
> see it if I do 'echo x > /proc/sysrq-trigger') . I wouldn't say
> it's "very early boot". It's a secondary CPU coming up and the primary
> is waiting for it. We've already configured the console when this
> happens.

Sounds like an early boot console.

>> > The output of 'dmesg' later looks always correct, right?
>
> No, dmesg also has the extra new lines: eg
>
> <4>NIP: c00000000004e234 LR: c00000000004e230 CTR: 0000000000000000
> <4>REGS: c00000007c3b7b50 TRAP: 0700 Tainted: G W (3.5.0-rc4-mikey)
> <4>MSR: 9000000000021032
> <4><
> <4>SF
> <4>,HV
> <4>,ME
> <4>,IR
> <4>,DR
> <4>,RI
> <4>>
> <4> CR: 28000042 XER: 22000000

Can you please paste the output of /dev/kmsg of this section? So we
can see the timestamps and what really went into the record buffer.

>> Could you possibly try this patch?
>
> Sorry, doesn't help. It also reprints the entire boot log to the
> console once the console get inited.

Which is the normal behaviour to do that, right? We should not have
touched any of that logic.

Thanks,
Kay