Opened 14 years ago

Closed 14 years ago

#247 closed enhancement (fixed)

Early kernel debugging

Reported by: Jiri Svoboda Owned by:
Priority: major Milestone: 0.4.3
Component: helenos/unspecified Version: mainline
Keywords: Cc:
Blocker for: Depends on:
See also:


Currently it is difficult to analyze failures in early stages of the kernel. The output devices are usually initialized in arch_post_mm_init() or arch_post_smp_init(). This is quite late. Often the most critical part of kernel initialization is the memory management init, yet at this stage no output is available.

Whenever I need to debug problems with MM initialization, I need to tediously add debug output messages by hand (via a specialized debug output routine).

This is a waste of time. Instead somehow it should be possible to enable early debug messages (that go to a real output devices, such as a serial console, not just to a kernel buffer).

While in a simulator it is possible to inspect the klog, this does not work on a real machine.

If it is not possible or advisable to initialize the full output-device machinery in such an early stage, there should be a simple debug-output mechanism added for each platform.

Change History (1)

comment:1 by Martin Decky, 14 years ago

Resolution: fixed
Status: newclosed

The framework has been implemented as of mainline,594, while platform-specific printout of debugging messages (any configurable kernel log output for that matter) is currently implemented for ia32 and amd64.

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