Le 08/11/2023 à 20:37, Arnd Bergmann a écrit :

On Wed, Nov 8, 2023, at 19:31, Christophe Leroy wrote:

quoted

Le 08/11/2023 à 13:58, Arnd Bergmann a écrit :

quoted

powerpc has functions doing more or less the same, they are called
__c_kernel_clock_gettime() and alike with their prototypes siting in
arch/powerpc/include/asm/vdso/gettimeofday.h

Should those prototypes be moved to include/vdso/gettime.h too and
eventually renamed, or are they considered too powerpc specific ?

I don't actually know, my initial interpretation was that
these function names are part of the user ABI for the vdso,
but I never looked closely enough at how vdso works to
be sure what the actual ABI is.

If __c_kernel_clock_gettime() etc are not part of the user-facing
ABI, I think renaming them for consistency with the other
architectures would be best.

User-facing ABI function is __kernel_clock_gettime(), defined in 
arch/powerpc/kernel/vdso/gettimeofday.S , see man vdso.
There is no prototype defined for it anywhere, obviously that's 
undetected because it is assembly. Should a prototype be added somewhere 
anyway ?

__kernel_clock_gettime() sets up a stack frame, retrieves the address of 
the datapage then calls __c_kernel_clock_gettime() which then calls 
__cvdso_clock_gettime_data() which is part of the generic CVDSO.

Maybe that's too different from what other architectures do ?

Christophe