Re: [PATCH 4/4] Add 32 bit VDSO time support for 64 bit kernel

H. Peter Anvin
2014-02-01T20:29:48Z

On 02/01/2014 07:32 AM, stefani@seibold.net wrote:
>
> This kind of type hacking could be prevent in the future by doing a call to the
> 64 bit code by the following sequence:
>
> - Compile the arch/x86/vdso/vclock_gettime.c as 64 bit, but only generate
> the assembler output.
> - Next compile a 32 bit object by including the 64 bit vclock_gettime.s
> prefixed with .code64
> - At least we need a trampolin code which invokes the 64 bit code and do
> the API conversation (64 bit longs to 32 bit longs), like the
> followig snipped:
>

Honestly, I think the overhead of the mode switch would ruin a lot of
the advantages with the vdso.

-hpa