Messages in this thread | | | Date | Wed, 24 Nov 2010 09:17:48 +0100 | From | Uwe Kleine-König <> | Subject | Re: About multi-line printk and the need (not) to repeat loglevel markers [Was: Re: [PATCH] ARM: mx3/pcm037: properly allocate memory for mx3-camera] |
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Hello Linus,
On Wed, Nov 24, 2010 at 07:16:06AM +0900, Linus Torvalds wrote: > 10/11/23 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>: > > > > BTW, I just noticed that Linus wrote: > > > > Additionally, if no newline existed, one is added (unless the > > log-level is the explicit KERN_CONT marker, to explicitly show > > that it's a continuation of a previous line). > > > > This seems to be unimplemented, otherwise the output of > > > > printk(KERN_ERR "foo bar baz "); > > printk("buz\n" KERN_WARNING "fiz\n"); > > > > should be > > > > "foo bar baz \n" at error level > > "buz\n<4>fiz\n" at default level > > No. The KERN_WARNING in the middle of a string is always totally > bogus. There is no "should be". It's just wrong. > > The "\n" is added automatically iff there is a log-level marker at the > beginning of the string (with LOG_CONT being the exception). So
printk("anything that doesn't look like a loglevel marker");
always behaves like
printk(KERN_CONT "anything that doesn't look like a loglevel marker");
so unless someone wants to print a literal kernel marker we can just do
-#define KERN_CONT "<c>" +#define KERN_CONT ""
without any harm.
I wonder why you implemented "iff there is a log-level marker at the beginning ot the string (with KERN_CONT being the exception)." and not "unless there is a KERN_CONT marker".
> So > > printk("foo bar baz "); > printk(KERN_WARNING "fiz\n"); > > should output two lines ("foo bar baz" with the default loglevel, and > "fiz" with KERN_WARNING). Even though there is no explicit "\n" there > for the first one. > > But KERN_XYZ anywhere but in the beginning of the string do not > matter. Adding newlines changes none of that. It doesn't make the > marker beginning of the string, it just makes it beginning of the > line. I see one reason to interpret markers after a newline. In case recursion_bug is true, printk_buf is initialized with recursion_bug_msg and my message gets appended. So currently the marker I pass with my message is ignored. Maybe wanting to fix that is just my addiction to overengineering :-)
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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