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=E2=80=99m trying to debug a potential kernel problem with POSIX = semaphores. I=E2=80=99m trying to build a custom kernel with some added = printf() statements and I=E2=80=99m 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.=20 Here=E2=80=99s what I=E2=80=99ve already done on my PC BSD 10.2 running = inside a VM =E2=80=94 =20 - Downloaded the source to /usr/src - Added a printf(=E2=80=9CHello world\n=E2=80=9D) 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=E2=80=99ve read is the = correct thing to do when one wants to use the kernel=E2=80=99s printf().=20= - cd /usr/src - sudo make buildkernel=20 - sudo make installkernel - reboot - Create a POSIX semaphore. It works, but I don=E2=80=99t see my = =E2=80=9CHello world=E2=80=9D message. Any suggestions on what I=E2=80=99m doing wrong would be appreciated. Thanks Philip
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