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Re: [PATCH] Add ABI mandated AT_ entries, prepare powerpc/dl-sysdep.c for new kernels


At 05:01 11.04.2001, Ulrich Drepper wrote:
>Geoff Keating <geoffk@geoffk.org> writes:
>
> > This is OK.  Do you have the ability to commit it?
>
>I'll check it in.  But are you all sure this patch is OK?  I have no
>problems with most of it but was unsure about the
>sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c change.  Is this code not
>necessary anymore?

Yes, it can go away with newer kernels. Newer kernels will generate a block 
of 4 AT_IGNOREPPC words (16bytes) at the start, making sure that the test 
"<=0x10" (or <=AT_PHDR in old glibc's) in powerpc/dl-sysdep.c doesn't 
trigger anymore. The only thing glibc has to do now is to never use the 
AT_IGNOREPPC value for real information.

Besides unifying the glibc code, the kernel code is much cheaper now too, 
as the expensive __get_user/__put_user memmove shifting of the AUXV can go 
away. The only overhead that remains are the 4 extra __put_user calls to 
setup the AT_IGNOREPPC block.

Franz.


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