Questions about VDSO

[Steve Munroe]

I am (finally) starting to look at enabling the GLIBC side of VDSO for 
PPC/PPC64 but have some questions about the details.

It looks like I need to define NEED_DL_SYSINFO in dl-sysdep.h  to set up 
the basic processing of AT_SYSINFO and AT_SYSINFO_EHDR. But looking at the 
i386 and ia64 examples it is not obvious what is needed for the general 
concept and what is specific to those platforms. For example I don't think 
PPC needs USE_DL_SYSINFO, DL_SYSINFO_DEFAULT, or DL_SYSINFO_IMPLEMENTATION 
because we are not changing the syscall mechanism for powerpc. Am I 
missing something?

Also there does not seem to be any kernel_feature specific enable for 
VDSO. So can I assume that a NEED_DL_SYSINFO GLIBC can run safely on a 
none VDSO kernel?

Steven J. Munroe
Linux on Power Toolchain Architect
IBM Corporation, Linux Technology Center