Messages in this thread | | | Date | Thu, 21 Sep 2000 18:54:33 -0400 (EDT) | From | Byron Stanoszek <> | Subject | Re: [DOC] Debugging early kernel hangs |
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On Fri, 22 Sep 2000, Keith Owens wrote:
> If a kernel hangs early in the boot process (before the console has > been initialized) then printk is no use because you never see the > output. There is a technique for using the video display to indicate > boot progress so you can localize the problem. Reporting "my kernel > hangs during boot at line nnn in routine xyz" is a lot better than "my > kernel hangs during boot". > > The idea is to write characters direct to the video screen during > booting using a macro called VIDEO_CHAR. This macro takes a character > position and a single character value to be displayed. Use different > positions on the screen for different levels of code and use different > characters in one position to indicate which stage that level is up to. > For example, with the patch below, the string EAC at hang indicates > parse_options(), checksetup().
Why not just redirect printk() to output a string of characters one by one using VIDEO_CHAR until the console subsystem is initialized. You can use a statically defined int to keep track of what row & column you're on. There is no need to be so cryptic about the readout.
Regards, Byron
-- Byron Stanoszek Ph: (330) 644-3059 Systems Programmer Fax: (330) 644-8110 Commercial Timesharing Inc. Email: bstanoszek@comtime.com
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