Why is CONFIG_MAGIC_SYSRQ enabled by default

hubx · 03-01-2011, 06:46 AM

Hey guys,

Today I stumbled upon Magic_SysRq_key. Basically, it's allows the user to perform various low level commands regardless of the system's state
e.g.
Alt+SysRq+b will reboot the system without syncing or unmounting.
(SysRq is Print on most systems.)

I see the point the use for kernel hackers and such, which compile their own kernels anyway, but why is this enabled by default?

--hub

Ramurd · 03-01-2011, 07:01 AM

Because it allows you to use these magic cmomands in case of a total freeze; If you think that this is a security issue, you can recomile your kernel without this option.

Martinezio · 03-01-2011, 07:04 AM

It's for recovering console from dead system (ie. when it's hanged by fallen X.org). Read the article to the end, and You will know why

REISUB is Your solution for that kind of crashes

But You should remember, that most peoples don't know this "feature" (whatever You will call it), so You shouldn't be affraid. But if You don't need this feature, You can easily disable it. And remember, that You must be at root privileges to write to /proc.

Cheers