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

Michael Neuling [off-list ref] wrote:

Kay Sievers [off-list ref] wrote:

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On Fri, Jul 6, 2012 at 2:41 AM, Michael Neuling [off-list ref] wrote:

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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.

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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.

Sure.

4,89,24561;NIP: c000000000048164 LR: c000000000048160 CTR: 0000000000000000
4,90,24576;REGS: c00000007e59fb50 TRAP: 0700   Tainted: G        W     (3.5.0-rc4-mikey)
4,91,24583;MSR: 9000000000021032 
4,92,24586;<
4,93,24591;SF
4,94,24596;,HV
4,95,24601;,ME
4,96,24606;,IR
4,97,24611;,DR
4,98,24616;,RI
4,99,24619;>
4,100,24628;  CR: 28000042  XER: 22000000

FWIW, compiling with the parent commit gives this:

4,89,1712;NIP: c000000000048164 LR: c000000000048160 CTR: 0000000000000000
4,90,1713;REGS: c00000007e59fb50 TRAP: 0700   Tainted: G        W     (3.5.0-rc4-mikey)
4,91,1716;MSR: 9000000000021032 <SF,HV,ME,IR,DR,RI>  CR: 22000082  XER: 02000000

Mikey

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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.

Not until this patch you asked me to try.  Hence why I noted it.  

Mikey