Created attachment 42556 [details] nops.c valgrind SIGILLs on some memset calls in Fedora 13 i686 glibc. Attached is a testcase which covers hopefully all possible instructions emitted by gas for various CPU tuning for alignment nops - except for jmps), for -m64 it works just fine, for -m32 valgrind doesn't grok any of the nopw insns wiht more than one data16 prefix.
Created attachment 42557 [details] valgrind-x86-nops.patch Fix.
Committed, vex r1978. Thanks for the patch.