Zack's Kernel News

Zack's Kernel News

Article from Issue 240/2020

Chronicler Zack Brown reports on a stone so large..., a global stats-gathering interface, and the Kernel development process.

A Stone So Large …

A lot of kernel patches just fix little things or make something slightly more convenient for system administrators and kernel developers. Recently, Joe Perches pointed out that the Arm architecture could conceivably invoke the Linux kernel with a command line that was longer than what printk() was able to output. So you could launch the kernel, but you couldn't then go back and see exactly how you'd done it.

He posted a patch to split long lines up so that printk() could output them.

Sergey Senozhatsky liked the overall idea, but pointed out a bug in Joe's code – he noted that printk() would also output a bit of prefix text, to let the user know what was being output. In this case, the prefix was "Kernel command line". Sergey reported that Joe's patch neglected to take the length of that prefix text into account when seeing whether the full output string was over the maximum size. So the text could still be slightly too big for printk(). Joe agreed and fixed it.


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