On 06/06/2014 12:25 PM, Michael Van Canneyt wrote:
if you do a vDSO implementation, please do not limit the
implementation to the clock_gettime, but implement all calls that
support it.
First testing results:
On Kernel 3.1.10 (32 bit):
- I do find the vDSO ELF structure (always at FFFFE000)
- it seems to provide "__kernel_sigreturn", "__kernel_rt_sigreturn" ,
and "__kernel_vsyscall"
On Kernel 3.2.0 64 bit, using a 32 Bit testing program:
- I do find the vDSO ELF structure at (e.g. at F774300, the location
varies for any program start. This behavior is documented for vDSO)
- it also seems to provide "just __kernel_sigreturn",
"__kernel_rt_sigreturn" , and "__kernel_vsyscall"
So I seem to be out of luck hoping for vDSO support for the performance
counter or similar arch depending time-source access with 32 bit systems
:-(
It _might_ be possible the __kernel_vsyscall could be done in a way that
it provides arch independent timer counter access that stays in user
mode if possible. I'll keep researching...
-Michael
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