Red Hat Bugzilla – Bug 426181
4.1.2 20070925 (Red Hat 4.1.2-33) -fstrict-aliasing causes skipped code
Last modified: 2007-12-19 02:55:00 EST
Description of problem:
This problem is described in detail in
Which says gnu.org's 4.1.2 is clean of this bug.
That fix needs to be backported to Redhat 4.1.2-33 and Fedora 4.1.2 20070925
Version-Release number of selected component (if applicable):
Fedora 4.1.2 20070925 (Redhat 4.1.2-33)
Steps to Reproduce:
The symptoms appear when compiling kernel module
The code that calls KEY_WLAN 1 and KEY_WLAN 0 is optimized out.
This is why Fedora 2.6.22-1.42 (f8 x86_64) worked in lighting the LED and
Fedora 2.6.22-1.49 (same arch) didn't. Same code, different compilation result.
There are additional examples in the references bugzillas... just thought I'd
add a Fedora-specific one. I'm not a compiler-internals guy. Just pointing out
this was patched in the gnu 4.1.2 but not in the RH/F 4.1.2.
Kernel modules should be compiled with -fno-strict-aliasing anyway, kernel
violates aliasing in hundreds of places.
If you read the PR properly, it would be clear this is a WONTFIX for 4.1.x/4.2.x,
the changes aren't really backportable to earlier GCC versions and are massive.