Re: calculus of PT_NOTE "for GNU/Linux 2.6.32"

This note comes from crt1.o, which is linked into every normal program (both static and dynamic). Off hand, I'm not sure of anything that actually checks this note. What it indicates is the minimum required kernel version that glibc was built for (its --enable-kernel configure option). This controls what system calls and such kernel features the libc code is built to assume exist and work correctly. In a statically-linked executable, there may very well be libc code that requires that new a kernel. The startup code in libc actually checks the kernel version against this, so a static executable won't try to run. For normal dynamically-linked executables, it is unlikely this note really means anything that matters. (I'm not entirely positive about this.) The same kernel requirement is built into all the DSOs in the glibc package, including the dynamic linker itself. The dynamic linker's startup code does the same kernel version check that is done by static libc code in a static link. But that is based on what those DSOs need, not what the crt1.o note in your executable says. For Fedora glibc builds, we have chosen the newest --enable-kernel version that we can use. (It is always more optimal to disable the compatibility code.) The limiting factor has been the kernels that the koji build machines run, so that glibc's build can do "make check" (actually the build itself requires running the just-built libc too). That's why it was 2.6.18 for so long, because those machines ran RHEL5. Now, I guess they run RHEL6 or something, so we can rely on getting 2.6.32. The proper and recommended way to build binaries that will be sure to be compatible with an older Fedora is to build them against the glibc-devel (and every other -devel) from that Fedora. I think most people use mock. Thanks, Roland