Date: Mon, 22 Feb 2016 21:01:46 -0500 From: Philip Semanchuk <philip@semanchuk.com> To: freebsd-questions@freebsd.org Subject: Adding printf() to observe semaphore behavior? Message-ID: <61DF564A-5DB5-4C9C-B12B-24CE529706D8@semanchuk.com>
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Hi all, I’m trying to debug a potential kernel problem with POSIX semaphores. I’m trying to build a custom kernel with some added printf() statements and I’m not seeing any output, neither to /var/log/messages nor to the console. I would appreciate any help at getting the kernel to talk to me. Here’s what I’ve already done on my PC BSD 10.2 running inside a VM — - Downloaded the source to /usr/src - Added a printf(“Hello world\n”) in each implementation of sem_open() (both in lib/libc/gen/sem.c and sem_new.c) and one inside the implementation of ksem_open() (in sys/kern/uipc_sem.c) for good measure. I did not #include <stdio.h> which I’ve read is the correct thing to do when one wants to use the kernel’s printf(). - cd /usr/src - sudo make buildkernel - sudo make installkernel - reboot - Create a POSIX semaphore. It works, but I don’t see my “Hello world” message. Any suggestions on what I’m doing wrong would be appreciated. Thanks Philiphelp
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