* Stefan Reinauer: > You raise a good point. The current implementation has glibc directly > reading from the vvar data page, which tightly couples glibc to the > kernel's internal vDSO memory layout. > > The more standard approach would be to export a __vdso_get_thread_area > function from the vDSO that glibc calls via the normal vDSO symbol > lookup mechanism. This would: > > 1. Follow the established vDSO pattern used by clock_gettime, > gettimeofday, etc. > 2. Allow the kernel to change the internal vvar layout without breaking > glibc > 3. Keep the ABI contract at the function level rather than data > structure level > > The tradeoff is a small amount of function call overhead, but that's > still much faster than the syscall we're replacing. > > I can rework this to export __vdso_get_thread_area from the vDSO and > have glibc use standard vDSO symbol lookup. Would that be the > preferred approach?
Yes, please do it this way. Thanks, Florian
