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kernel boot arguments

Posted by egstern 
kernel boot arguments
January 26, 2011 10:12AM
I have Debian reliably booting on my dockstar with netconsole enabled so I can see the uBoot messages. I'm familiar with passing arguments to the kernel with regular desktop linux installs, so I'm wondering where or whether the kernel receives boot arguments. I recongnize the root= option as a kernel parameter. The generic linux kernel may support a netconsole parameter netconsole parameter documentation. Does the kernel that goes with the Debian install support that? Would I add the netconsole options to usb_custom_params? Is there any danger in this?
Re: kernel boot arguments
January 26, 2011 10:51AM
egstern Wrote:
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> Would I add the netconsole options to usb_custom_params?

I used the usb_customs_params to pass additional argments to the kernel.. In my case I was trying to boot the armedSlack installer with out the need of a serial cable so I had to pass both keyboard and network options to get to the point where I could ssh into it. So I used the following command from, in my case, the rescue system prompt:

fw_setenv usb_custom_params nic=auto:eth0:dhcp kbd=uk

Once I added that to the ubout enviorment I was able to boot into the armedSlack installer and ssh into to login prompt.
Re: kernel boot arguments
January 26, 2011 02:24PM
Without a hardwired console, it is always a potentially dangerous thing to mess with the uBoot environment, which of course, you must do if you want to change the kernel's boot arguments. The boot arguments (you can see what they are by executing "cat /proc/cmdline" after Debian has booted) are set in usb_bootcmd by the usb_set_bootargs variable, and yes, usb_custom_params may be used to add additional arguments to the kernel's cmdline. Probably the safest approach is to use netconsole to set this variable temporarily first, in order to see if it has the desired effect, and then commit it to the uBoot's environment if it indeed works.



Edited 1 time(s). Last edit at 01/26/2011 02:24PM by restamp.
ano
Re: kernel boot arguments
February 09, 2011 11:08AM
would that be the right command on the dockstar to debug kernel messages via another machine ?

fw_setenv usb_custom_params netconsole=6666@<ip dockstar>/eth0,6666@<ip server>/<mac addr server>
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