Redirecting output message while inserting a new device

niiiro · 12-28-2010, 05:45 AM

Hey Guys,

When inserting/removing a usb device to a board based on linux system, an output is given:

Code:

# mmc1: card 0001 removed

mmc1: new SD card at address 0001
mmcblk1: mmc1:0001 128MB 110 MiB
 mmcblk1:<7>mmc1: starting CMD18 arg 00000000 flags 000000b5
 p1

how can I redirect its default output so it will write it to a file instead?

thanks in advanced.

Nir.

Oliv' · 12-28-2010, 07:34 AM

Hello,

I think taht adding "console=null" on your kernel command line should do the trick.

Kind regards,

Oliv'

niiiro · 12-28-2010, 09:26 AM

Hey Oliv' and thanks for your reply.

unfortunately that didn't do the trick. I even tried directing him to a file by doing:

"console=~\file.txt" but no good..

Oliv' · 12-28-2010, 10:58 AM

ah yes, my method may only work to disable kernel log through serial console. In fact console argument on kernel command line requires a /dev file. So redirecting to the file is not so easy.... I will think a bit more about your problems and tell you if I find a solution.

Kind regards

niiiro · 12-29-2010, 02:37 AM

Thanks Oliv'.

In the meanwhile, has anyone else got a solution maybe...?

Oliv' · 12-29-2010, 12:40 PM

Well I see 2 potentials solutions, but I am not sure it will work as I have not tested them.
1) configure syslogd to handle that... and maybe even install it as it seems you use an embedded device, so I am nopt sure that's already installed.
2) these messages are due to printk() function in the kernel. So you may hack some kernel parts to directly log these message into a file. But it implies that you have some basic kernel coding knowledge.

Regards,

Oliv'

teckk · 12-29-2010, 03:59 PM

Isn't that info being appended to dmesg whenever you plugin or remove a usb device?

For a BSD box

Code:

$ dmesg | tail
da0: 40.000MB/s transfers
da0: Attempt to query device size failed: NOT READY, Medium not present
ulpt0: at uhub3 port 2 (addr 2) disconnected
ulpt0: detached
umass0: at uhub3 port 2 (addr 2) disconnected
(da0:umass-sim0:0:0:0): lost device
(da0:umass-sim0:0:0:0): removing device entry
umass0: detached

Where does dmesg keep it's log file on that Linux box?

/var/log/messages

Code:

Dec 29 11:06:05 hostname kernel: ulpt0: at uhub3 port 2 (addr 2) disconnected
Dec 29 11:06:05 hostname kernel: ulpt0: detached
Dec 29 11:06:05 hostname kernel: umass0: at uhub3 port 2 (addr 2) disconnected
Dec 29 11:06:05 hostname kernel: (da0:umass-sim0:0:0:0): lost device
Dec 29 11:06:05 hostname kernel: (da0:umass-sim0:0:0:0): removing device entry
Dec 29 11:06:05 hostname kernel: umass0: detached