Re: [RFC][PATCH] printk: add console_msg_format command line option
On (12/07/17 16:45), Petr Mladek wrote: [.,] > > hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw' > > matches the console_msg_format=syslog. > > Huh, I am confused now. I thought that I saw the extended, /dev/kmsg - like, > output with "dmesg --raw" but I do not see it now. > > Anyway, I can see a difference related to > /sys/module/printk/parameters/time. The command "dmesg --raw" always > shows the timestamp help because it reads the messages via /dev/kmsg. > But "dmesg -S --raw" shows the timestamp only when the "time" > parameter is enabled: aha, I see your point. -S forces dmesg to use syslog() syscall. so it doesn't access the kmsg. otherwise it attempts to read from kmsg first. you are right. > $> echo 0 >/sys/module/printk/parameters/time > $> dmesg -S --raw | head -n 3 > <5>Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 > (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 > <6>Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ > root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 > earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 > console_msg_format=syslog ignore_loglevel nosplash showopts > crashkernel=256M,high crashkernel=128M,low > <6>x86/fpu: x87 FPU will use FXSAVE > $> echo 1 >/sys/module/printk/parameters/time > $> dmesg -S --raw | head -n 3 > <5>[0.00] Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc > version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 > <6>[0.00] Command line: > BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ > root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 > earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 > console_msg_format=syslog ignore_loglevel nosplash showopts > crashkernel=256M,high crashkernel=128M,low > <6>[0.00] x86/fpu: x87 FPU will use FXSAVE I see. > To be honest, I am somehow confused by the terminology. > We should make it clear that the "syslog" console format > is the same as the format used by the syslog syscall. yeah. that was exactly my point. syslog format means that : we do what reading from /proc/kmsg does -- do_syslog(). which "is" : the same for some dmesg modes. I thought that `dmesg --raw' always uses do_syslog(), apparently this is not the case, and that "is" was not correct. -ss
Re: [RFC][PATCH] printk: add console_msg_format command line option
On (12/07/17 16:45), Petr Mladek wrote: [.,] > > hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw' > > matches the console_msg_format=syslog. > > Huh, I am confused now. I thought that I saw the extended, /dev/kmsg - like, > output with "dmesg --raw" but I do not see it now. > > Anyway, I can see a difference related to > /sys/module/printk/parameters/time. The command "dmesg --raw" always > shows the timestamp help because it reads the messages via /dev/kmsg. > But "dmesg -S --raw" shows the timestamp only when the "time" > parameter is enabled: aha, I see your point. -S forces dmesg to use syslog() syscall. so it doesn't access the kmsg. otherwise it attempts to read from kmsg first. you are right. > $> echo 0 >/sys/module/printk/parameters/time > $> dmesg -S --raw | head -n 3 > <5>Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 > (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 > <6>Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ > root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 > earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 > console_msg_format=syslog ignore_loglevel nosplash showopts > crashkernel=256M,high crashkernel=128M,low > <6>x86/fpu: x87 FPU will use FXSAVE > $> echo 1 >/sys/module/printk/parameters/time > $> dmesg -S --raw | head -n 3 > <5>[0.00] Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc > version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 > <6>[0.00] Command line: > BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ > root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 > earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 > console_msg_format=syslog ignore_loglevel nosplash showopts > crashkernel=256M,high crashkernel=128M,low > <6>[0.00] x86/fpu: x87 FPU will use FXSAVE I see. > To be honest, I am somehow confused by the terminology. > We should make it clear that the "syslog" console format > is the same as the format used by the syslog syscall. yeah. that was exactly my point. syslog format means that : we do what reading from /proc/kmsg does -- do_syslog(). which "is" : the same for some dmesg modes. I thought that `dmesg --raw' always uses do_syslog(), apparently this is not the case, and that "is" was not correct. -ss
Re: [RFC][PATCH] printk: add console_msg_format command line option
On Thu 2017-12-07 23:01:04, Sergey Senozhatsky wrote: > Hi, > > On (12/07/17 14:48), Petr Mladek wrote: > [..] > > > This patch introduces a `console_msg_format=' command line option, > > > to switch between different message formatting on serial consoles. > > > For the time being we have just one option - syslog. This option > > > makes serial console messages to appear in syslog format, matching > > > the `dmesg --raw' and `cat /proc/kmsg' output formats: > > > > I have realized that 'cat /proc/kmsg' did not work. It can be done using: > > hm, it does work on my system. what do you mean by 'did not work'? > > > > Also the format is more comlicated here, see printk.c: > > > > * /dev/kmsg exports the structured data in the following line format: > > * ",,,[,additional_values, ... > > ];\n" > > that's /dev/kmsg. /dev/kmsg != /proc/kmsg. I never mentioned /dev/kmsg > in my commit. /dev/kmsg prints the extended stuff, /proc/kmsg does not. Ah, I have messed /dev/kmsg and /proc/kmsg. > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > > > b/Documentation/admin-guide/kernel-parameters.txt > > > index 28467638488d..2dd91c5073f9 100644 > > > --- a/Documentation/admin-guide/kernel-parameters.txt > > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > > @@ -643,6 +643,16 @@ > > > console=brl,ttyS0 > > > For now, only VisioBraille is supported. > > > > > > + console_msg_format= > > > + [KNL] Control message format > > > + By default we print messages in "[time stamp] text\n" > > > + format (time stamp may not be printed, depending on > > > + CONFIG_PRINTK_TIME or `printk_time' param). > > > + syslog > > > + Switch to syslog format (similar to "dmesg --raw" or > > > + reading from /proc/kmsg): "<%u>[time stamp] text\n" > > > > To be precise, it exactly the same as "dmesg -S --raw". Also it is the > > format used by SYSLOG_ACTION_READ* actions of the syslog syscall. > > hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw' > matches the console_msg_format=syslog. Huh, I am confused now. I thought that I saw the extended, /dev/kmsg - like, output with "dmesg --raw" but I do not see it now. Anyway, I can see a difference related to /sys/module/printk/parameters/time. The command "dmesg --raw" always shows the timestamp help because it reads the messages via /dev/kmsg. But "dmesg -S --raw" shows the timestamp only when the "time" parameter is enabled: $> echo 0 >/sys/module/printk/parameters/time $> dmesg -S --raw | head -n 3 <5>Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 <6>Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 console_msg_format=syslog ignore_loglevel nosplash showopts crashkernel=256M,high crashkernel=128M,low <6>x86/fpu: x87 FPU will use FXSAVE $> echo 1 >/sys/module/printk/parameters/time $> dmesg -S --raw | head -n 3 <5>[0.00] Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 <6>[0.00] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 console_msg_format=syslog ignore_loglevel nosplash showopts crashkernel=256M,high crashkernel=128M,low <6>[0.00] x86/fpu: x87 FPU will use FXSAVE Note that the -S option has been added in util-linux, v2.22 by the commit https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=ed61acc2542ebb0d9b8f5600c38fbe0d77933345 I guess that dmesg fallbacks to the classic syslog mode when /dev/kmsg is not available. To be honest, I am somehow confused by the terminology. We should make it clear that the "syslog" console format is the same as the format used by the syslog syscall. dmesg --raw might show something different when it gets the data from /dev/kmsg as shown above. Best Regards, Petr
Re: [RFC][PATCH] printk: add console_msg_format command line option
On Thu 2017-12-07 23:01:04, Sergey Senozhatsky wrote: > Hi, > > On (12/07/17 14:48), Petr Mladek wrote: > [..] > > > This patch introduces a `console_msg_format=' command line option, > > > to switch between different message formatting on serial consoles. > > > For the time being we have just one option - syslog. This option > > > makes serial console messages to appear in syslog format, matching > > > the `dmesg --raw' and `cat /proc/kmsg' output formats: > > > > I have realized that 'cat /proc/kmsg' did not work. It can be done using: > > hm, it does work on my system. what do you mean by 'did not work'? > > > > Also the format is more comlicated here, see printk.c: > > > > * /dev/kmsg exports the structured data in the following line format: > > * ",,,[,additional_values, ... > > ];\n" > > that's /dev/kmsg. /dev/kmsg != /proc/kmsg. I never mentioned /dev/kmsg > in my commit. /dev/kmsg prints the extended stuff, /proc/kmsg does not. Ah, I have messed /dev/kmsg and /proc/kmsg. > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > > > b/Documentation/admin-guide/kernel-parameters.txt > > > index 28467638488d..2dd91c5073f9 100644 > > > --- a/Documentation/admin-guide/kernel-parameters.txt > > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > > @@ -643,6 +643,16 @@ > > > console=brl,ttyS0 > > > For now, only VisioBraille is supported. > > > > > > + console_msg_format= > > > + [KNL] Control message format > > > + By default we print messages in "[time stamp] text\n" > > > + format (time stamp may not be printed, depending on > > > + CONFIG_PRINTK_TIME or `printk_time' param). > > > + syslog > > > + Switch to syslog format (similar to "dmesg --raw" or > > > + reading from /proc/kmsg): "<%u>[time stamp] text\n" > > > > To be precise, it exactly the same as "dmesg -S --raw". Also it is the > > format used by SYSLOG_ACTION_READ* actions of the syslog syscall. > > hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw' > matches the console_msg_format=syslog. Huh, I am confused now. I thought that I saw the extended, /dev/kmsg - like, output with "dmesg --raw" but I do not see it now. Anyway, I can see a difference related to /sys/module/printk/parameters/time. The command "dmesg --raw" always shows the timestamp help because it reads the messages via /dev/kmsg. But "dmesg -S --raw" shows the timestamp only when the "time" parameter is enabled: $> echo 0 >/sys/module/printk/parameters/time $> dmesg -S --raw | head -n 3 <5>Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 <6>Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 console_msg_format=syslog ignore_loglevel nosplash showopts crashkernel=256M,high crashkernel=128M,low <6>x86/fpu: x87 FPU will use FXSAVE $> echo 1 >/sys/module/printk/parameters/time $> dmesg -S --raw | head -n 3 <5>[0.00] Linux version 4.15.0-rc2-5-default+ (pmladek@pathway) (gcc version 4.8.5 (SUSE Linux)) #4180 SMP Thu Dec 7 16:06:42 CET 2017 <6>[0.00] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-rc2-5-default+ root=UUID=9ba368bb-c323-4131-ad94-c29cf3add76f resume=/dev/sda2 earlyprintk=ttyS0,115200 console=tty0 console=ttyS0,115200 console_msg_format=syslog ignore_loglevel nosplash showopts crashkernel=256M,high crashkernel=128M,low <6>[0.00] x86/fpu: x87 FPU will use FXSAVE Note that the -S option has been added in util-linux, v2.22 by the commit https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=ed61acc2542ebb0d9b8f5600c38fbe0d77933345 I guess that dmesg fallbacks to the classic syslog mode when /dev/kmsg is not available. To be honest, I am somehow confused by the terminology. We should make it clear that the "syslog" console format is the same as the format used by the syslog syscall. dmesg --raw might show something different when it gets the data from /dev/kmsg as shown above. Best Regards, Petr
Re: [RFC][PATCH] printk: add console_msg_format command line option
Hi,
On (12/07/17 14:48), Petr Mladek wrote:
[..]
> > This patch introduces a `console_msg_format=' command line option,
> > to switch between different message formatting on serial consoles.
> > For the time being we have just one option - syslog. This option
> > makes serial console messages to appear in syslog format, matching
> > the `dmesg --raw' and `cat /proc/kmsg' output formats:
>
> I have realized that 'cat /proc/kmsg' did not work. It can be done using:
hm, it does work on my system. what do you mean by 'did not work'?
> Also the format is more comlicated here, see printk.c:
>
> * /dev/kmsg exports the structured data in the following line format:
> * ",,,[,additional_values, ...
> ];\n"
that's /dev/kmsg. /dev/kmsg != /proc/kmsg. I never mentioned /dev/kmsg
in my commit. /dev/kmsg prints the extended stuff, /proc/kmsg does not.
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt
> > b/Documentation/admin-guide/kernel-parameters.txt
> > index 28467638488d..2dd91c5073f9 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -643,6 +643,16 @@
> > console=brl,ttyS0
> > For now, only VisioBraille is supported.
> >
> > + console_msg_format=
> > + [KNL] Control message format
> > + By default we print messages in "[time stamp] text\n"
> > + format (time stamp may not be printed, depending on
> > + CONFIG_PRINTK_TIME or `printk_time' param).
> > + syslog
> > + Switch to syslog format (similar to "dmesg --raw" or
> > + reading from /proc/kmsg): "<%u>[time stamp] text\n"
>
> To be precise, it exactly the same as "dmesg -S --raw". Also it is the
> format used by SYSLOG_ACTION_READ* actions of the syslog syscall.
hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw'
matches the console_msg_format=syslog.
> > +static int __init console_msg_format_setup(char *str)
> > +{
> > + if (!strncmp(str, "syslog", 6))
> > + console_msg_format = MSG_FORMAT_SYSLOG;
>
> It might make sense to accept also the "default" format.
>
> > + return 1;
> > +}
> > +__setup("console_msg_format=", console_msg_format_setup);
>
> I would use early_param() so that it takes effect as soon as possible.
ok. can take a look.
-ss
Re: [RFC][PATCH] printk: add console_msg_format command line option
Hi,
On (12/07/17 14:48), Petr Mladek wrote:
[..]
> > This patch introduces a `console_msg_format=' command line option,
> > to switch between different message formatting on serial consoles.
> > For the time being we have just one option - syslog. This option
> > makes serial console messages to appear in syslog format, matching
> > the `dmesg --raw' and `cat /proc/kmsg' output formats:
>
> I have realized that 'cat /proc/kmsg' did not work. It can be done using:
hm, it does work on my system. what do you mean by 'did not work'?
> Also the format is more comlicated here, see printk.c:
>
> * /dev/kmsg exports the structured data in the following line format:
> * ",,,[,additional_values, ...
> ];\n"
that's /dev/kmsg. /dev/kmsg != /proc/kmsg. I never mentioned /dev/kmsg
in my commit. /dev/kmsg prints the extended stuff, /proc/kmsg does not.
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt
> > b/Documentation/admin-guide/kernel-parameters.txt
> > index 28467638488d..2dd91c5073f9 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -643,6 +643,16 @@
> > console=brl,ttyS0
> > For now, only VisioBraille is supported.
> >
> > + console_msg_format=
> > + [KNL] Control message format
> > + By default we print messages in "[time stamp] text\n"
> > + format (time stamp may not be printed, depending on
> > + CONFIG_PRINTK_TIME or `printk_time' param).
> > + syslog
> > + Switch to syslog format (similar to "dmesg --raw" or
> > + reading from /proc/kmsg): "<%u>[time stamp] text\n"
>
> To be precise, it exactly the same as "dmesg -S --raw". Also it is the
> format used by SYSLOG_ACTION_READ* actions of the syslog syscall.
hmm... `dmesg -S --raw' doesn't show anything on my system. `dmesg --raw'
matches the console_msg_format=syslog.
> > +static int __init console_msg_format_setup(char *str)
> > +{
> > + if (!strncmp(str, "syslog", 6))
> > + console_msg_format = MSG_FORMAT_SYSLOG;
>
> It might make sense to accept also the "default" format.
>
> > + return 1;
> > +}
> > +__setup("console_msg_format=", console_msg_format_setup);
>
> I would use early_param() so that it takes effect as soon as possible.
ok. can take a look.
-ss
Re: [RFC][PATCH] printk: add console_msg_format command line option
On Fri 2017-12-01 19:44:04, Sergey Senozhatsky wrote:
> 0day and kernelCI automatically parse kernel log - basically some sort
> of grepping using the pre-defined text patterns - in order to detect
> and report regressions/errors. There are several sources they get the
> kernel logs from:
>
> a) dmesg or /proc/ksmg
>
>This is the preferred way. Because `dmesg --raw' and /proc/kmsg
>output contains facility and log level, which greatly simplifies
>grepping for EMERG/ALERT/CRIT/ERR messages.
>
> b) serial consoles
>
>This option is harder to maintain, because serial console messages
>don't contain facility and log level.
>
> This patch introduces a `console_msg_format=' command line option,
> to switch between different message formatting on serial consoles.
> For the time being we have just one option - syslog. This option
> makes serial console messages to appear in syslog format, matching
> the `dmesg --raw' and `cat /proc/kmsg' output formats:
I have realized that 'cat /proc/kmsg' did not work. It can be done using:
dd if=/dev/kmsg iflag=nonblock
Also the format is more comlicated here, see printk.c:
* /dev/kmsg exports the structured data in the following line format:
* ",,,[,additional_values, ...
];\n"
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 28467638488d..2dd91c5073f9 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -643,6 +643,16 @@
> console=brl,ttyS0
> For now, only VisioBraille is supported.
>
> + console_msg_format=
> + [KNL] Control message format
> + By default we print messages in "[time stamp] text\n"
> + format (time stamp may not be printed, depending on
> + CONFIG_PRINTK_TIME or `printk_time' param).
> + syslog
> + Switch to syslog format (similar to "dmesg --raw" or
> + reading from /proc/kmsg): "<%u>[time stamp] text\n"
To be precise, it exactly the same as "dmesg -S --raw". Also it is the
format used by SYSLOG_ACTION_READ* actions of the syslog syscall.
Note that it is affected by CONFIG_PRINTK_TIME or "printk_time" command-line
option the same way as the default format.
> + IOW, each message has a facility and loglevel prefix.
> +
> consoleblank= [KNL] The console blank (screen saver) timeout in
> seconds. A value of 0 disables the blank timer.
> Defaults to 0.
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 5d81206a572d..012a6b4991a6 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -277,6 +277,13 @@ EXPORT_SYMBOL(console_set_on_cmdline);
> /* Flag: console code may call schedule() */
> static int console_may_schedule;
>
> +enum con_msg_format {
> + MSG_FORMAT_DEFAULT = 0,
> + MSG_FORMAT_SYSLOG = (1 << 0),
> +};
> +
> +static int console_msg_format = MSG_FORMAT_DEFAULT;
> +
> /*
> * The printk log buffer consists of a chain of concatenated variable
> * length records. Every record starts with a record header, containing
> @@ -1913,6 +1920,15 @@ static int __add_preferred_console(char *name, int
> idx, char *options,
> c->index = idx;
> return 0;
> }
> +
> +static int __init console_msg_format_setup(char *str)
> +{
> + if (!strncmp(str, "syslog", 6))
> + console_msg_format = MSG_FORMAT_SYSLOG;
It might make sense to accept also the "default" format.
> + return 1;
> +}
> +__setup("console_msg_format=", console_msg_format_setup);
I would use early_param() so that it takes effect as soon as possible.
Otherwise, it looks fine. The patch is nicely minimalistic.
Best Regards,
Petr
Re: [RFC][PATCH] printk: add console_msg_format command line option
On Fri 2017-12-01 19:44:04, Sergey Senozhatsky wrote:
> 0day and kernelCI automatically parse kernel log - basically some sort
> of grepping using the pre-defined text patterns - in order to detect
> and report regressions/errors. There are several sources they get the
> kernel logs from:
>
> a) dmesg or /proc/ksmg
>
>This is the preferred way. Because `dmesg --raw' and /proc/kmsg
>output contains facility and log level, which greatly simplifies
>grepping for EMERG/ALERT/CRIT/ERR messages.
>
> b) serial consoles
>
>This option is harder to maintain, because serial console messages
>don't contain facility and log level.
>
> This patch introduces a `console_msg_format=' command line option,
> to switch between different message formatting on serial consoles.
> For the time being we have just one option - syslog. This option
> makes serial console messages to appear in syslog format, matching
> the `dmesg --raw' and `cat /proc/kmsg' output formats:
I have realized that 'cat /proc/kmsg' did not work. It can be done using:
dd if=/dev/kmsg iflag=nonblock
Also the format is more comlicated here, see printk.c:
* /dev/kmsg exports the structured data in the following line format:
* ",,,[,additional_values, ...
];\n"
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 28467638488d..2dd91c5073f9 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -643,6 +643,16 @@
> console=brl,ttyS0
> For now, only VisioBraille is supported.
>
> + console_msg_format=
> + [KNL] Control message format
> + By default we print messages in "[time stamp] text\n"
> + format (time stamp may not be printed, depending on
> + CONFIG_PRINTK_TIME or `printk_time' param).
> + syslog
> + Switch to syslog format (similar to "dmesg --raw" or
> + reading from /proc/kmsg): "<%u>[time stamp] text\n"
To be precise, it exactly the same as "dmesg -S --raw". Also it is the
format used by SYSLOG_ACTION_READ* actions of the syslog syscall.
Note that it is affected by CONFIG_PRINTK_TIME or "printk_time" command-line
option the same way as the default format.
> + IOW, each message has a facility and loglevel prefix.
> +
> consoleblank= [KNL] The console blank (screen saver) timeout in
> seconds. A value of 0 disables the blank timer.
> Defaults to 0.
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 5d81206a572d..012a6b4991a6 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -277,6 +277,13 @@ EXPORT_SYMBOL(console_set_on_cmdline);
> /* Flag: console code may call schedule() */
> static int console_may_schedule;
>
> +enum con_msg_format {
> + MSG_FORMAT_DEFAULT = 0,
> + MSG_FORMAT_SYSLOG = (1 << 0),
> +};
> +
> +static int console_msg_format = MSG_FORMAT_DEFAULT;
> +
> /*
> * The printk log buffer consists of a chain of concatenated variable
> * length records. Every record starts with a record header, containing
> @@ -1913,6 +1920,15 @@ static int __add_preferred_console(char *name, int
> idx, char *options,
> c->index = idx;
> return 0;
> }
> +
> +static int __init console_msg_format_setup(char *str)
> +{
> + if (!strncmp(str, "syslog", 6))
> + console_msg_format = MSG_FORMAT_SYSLOG;
It might make sense to accept also the "default" format.
> + return 1;
> +}
> +__setup("console_msg_format=", console_msg_format_setup);
I would use early_param() so that it takes effect as soon as possible.
Otherwise, it looks fine. The patch is nicely minimalistic.
Best Regards,
Petr
