Zack's Kernel News
Zack's Kernel News
Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.
Cheaper Oops Output
David Herrmann pointed out that the VT (virtual terminal) subsystem was not really needed for system consoles anymore, but trying to save space in the kernel binary by disabling the VT subsystem compile-time option would cause another problem – the kernel wouldn't send oops output to the console in the event of a kernel panic. David wanted to find a way to preserve oops output while disabling the VT subsystem.
He posted a patch to implement DRM-log (direct rendering manager). This registered its own console and pushed kernel logging messages (including oops output) to it as needed.
One of the fun things about code that outputs oops logs is that it can't really rely on the full infrastructure of the system. After all, the system just crashed and is using its dying gasp to send a message to the future. Fires and explosions could be everywhere, so DRM-log had to worry about things like wrapping the lines of the log and fitting them visually into the framebuffer, pixel by pixel, drawing everything out onto a screen that might be the only thing left standing.
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