Most recent kernel where this bug did *NOT* occur: Distribution: Debian Hardware Environment: Clevo model D4J, product code D410J Software Environment: Problem Description: The "cat /proc/acpi/debug_level" command result in a truncated output when executing from an xterm window. When the same command is redirected to file, the output is not truncated. The strace analysis shows that the "cat" command executes a system read with a buffer size of 1024, then repeats with a second read() to fetch the remaining part of the output. The remaining part is not returned by read() in this case. If the output of "cat" is redirected to file, it will use a buffer sized 4096 bytes, so the full output is catched with one read() call. Steps to reproduce: in xterm window: cat /proc/acpi/debug_level cat /proc/acpi/debug_level >to_file.txt
Created attachment 11605 [details] strace output when cat to stdout
Created attachment 11606 [details] strace output when cat to file
change to seqfile interface should fix the issue.
That's true. But the sysfs I/F for ACPI debug is available now, i.e. /sys/modules/acpi/parameters/debug_level and debug_layer. As the proc interface of ACPI is going to be removed, we won't fix it. :) *** This bug has been marked as a duplicate of 5076 ***