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Message-ID: <CAMuHMdVEKpVYn+Yr5rzdOvV5zUWrD12Fas197Mn2oVDC5YgVgw@mail.gmail.com>
Date: Thu, 16 Aug 2012 15:17:47 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: uml-devel <user-mode-linux-devel@...ts.sourceforge.net>,
linux-kbuild <linux-kbuild@...r.kernel.org>,
Joe Perches <joe@...ches.com>
Cc: linux-kernel@...r.kernel.org
Subject: Regression: Spurious "^A" in UML output
In v3.6-rc1 UML, I see spurious "^A" (ASCII 1, SOH) characters in some kernel
messages:
Calibrating delay loop... 4640.76 BogoMIPS (lpj=23203840)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 256
^AChecking that host ptys support output SIGIO...Yes
^AChecking that host ptys support SIGIO on close...No, enabling workaround
^AUsing 2.6 host AIO
NET: Registered protocol family 16
bio: create slab <bio-0> at 0
Switching to clocksource itimer
This happens for all output using the "printk(UM_KERN_XXX ...)" idiom.
The "UM_KERN_XXX" defines are generated from the KERN_XXX defines in
arch/um/include/shared/common-offsets.h using:
DEFINE_STR(UM_KERN_EMERG, KERN_EMERG);
DEFINE_STR(UM_KERN_ALERT, KERN_ALERT);
DEFINE_STR(UM_KERN_CRIT, KERN_CRIT);
DEFINE_STR(UM_KERN_ERR, KERN_ERR);
DEFINE_STR(UM_KERN_WARNING, KERN_WARNING);
DEFINE_STR(UM_KERN_NOTICE, KERN_NOTICE);
DEFINE_STR(UM_KERN_INFO, KERN_INFO);
DEFINE_STR(UM_KERN_DEBUG, KERN_DEBUG);
DEFINE_STR(UM_KERN_CONT, KERN_CONT);
Before commit 04d2c8c83d0e3ac5f78aeede51babb3236200112 ("printk: convert
the format for KERN_<LEVEL> to a 2 byte pattern"), these were expanded in
include/generated/asm-offsets.h to:
#define UM_KERN_EMERG "<0>" /* KERN_EMERG */
#define UM_KERN_ALERT "<1>" /* KERN_ALERT */
#define UM_KERN_CRIT "<2>" /* KERN_CRIT */
#define UM_KERN_ERR "<3>" /* KERN_ERR */
#define UM_KERN_WARNING "<4>" /* KERN_WARNING */
#define UM_KERN_NOTICE "<5>" /* KERN_NOTICE */
#define UM_KERN_INFO "<6>" /* KERN_INFO */
#define UM_KERN_DEBUG "<7>" /* KERN_DEBUG */
#define UM_KERN_CONT "<c>" /* KERN_CONT */
In v3.6-rc1, they expand to:
#define UM_KERN_EMERG "\001" /* "0" KERN_EMERG */
#define UM_KERN_ALERT "\001" /* "1" KERN_ALERT */
#define UM_KERN_CRIT "\001" /* "2" KERN_CRIT */
#define UM_KERN_ERR "\001" /* "3" KERN_ERR */
#define UM_KERN_WARNING "\001" /* "4" KERN_WARNING */
#define UM_KERN_NOTICE "\001" /* "5" KERN_NOTICE */
#define UM_KERN_INFO "\001" /* "6" KERN_INFO */
#define UM_KERN_DEBUG "\001" /* "7" KERN_DEBUG */
#define UM_KERN_CONT "\001" /* "c" KERN_CONT */
I.e. only the SOH character is retained in the actual define, the remainder ends
up in the comment.
Apparently the combo of DEFINE_STR() in
arch/x86/um/shared/sysdep/kernel-offsets.h
and sed-y in Kbuild doesn't support string constants consisting of
multiple parts.
A quick fix is the (whitespace-damaged) patch below, but this would reduce
readability. And I'm afraid my sed-foo is not good enough to fix it better.
Any takers?
diff --git a/include/linux/kern_levels.h b/include/linux/kern_levels.h
index 866caaa..1c43b52 100644
--- a/include/linux/kern_levels.h
+++ b/include/linux/kern_levels.h
@@ -4,16 +4,16 @@
#define KERN_SOH "\001" /* ASCII Start Of Header */
#define KERN_SOH_ASCII '\001'
-#define KERN_EMERG KERN_SOH "0" /* system is unusable */
-#define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
-#define KERN_CRIT KERN_SOH "2" /* critical conditions */
-#define KERN_ERR KERN_SOH "3" /* error conditions */
-#define KERN_WARNING KERN_SOH "4" /* warning conditions */
-#define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */
-#define KERN_INFO KERN_SOH "6" /* informational */
-#define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
+#define KERN_EMERG "\0010" /* system is unusable */
+#define KERN_ALERT "\0011" /* action must be taken immediately */
+#define KERN_CRIT "\0012" /* critical conditions */
+#define KERN_ERR "\0013" /* error conditions */
+#define KERN_WARNING "\0014" /* warning conditions */
+#define KERN_NOTICE "\0015" /* normal but significant condition */
+#define KERN_INFO "\0016" /* informational */
+#define KERN_DEBUG "\0017" /* debug-level messages */
-#define KERN_DEFAULT KERN_SOH "d" /* the default kernel loglevel */
+#define KERN_DEFAULT "\001d" /* the default kernel loglevel */
/*
* Annotation for a "continued" line of log printout (only done after a
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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