[PATCH 4/6] aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK

[Siddhesh Poyarekar]

On Wednesday 07 June 2017 08:30 PM, Szabolcs Nagy wrote:
> OK if the new HWCAP_IMPORTANT does not cause
> additional open/stat/.. syscalls (please verify
> that the lib search path is not increased by
> running something like
> strace -E LD_PRELOAD=foobar.so /bin/true
> and counting the failed syscalls)
> 
> (if the search path is increased then i'd like
> to know what is the purpose of that feature)

I thought I already explained it in a previous email - this adds an
additional search path for the dynamic linker to look for libraries that
may be optimized for that specific hwcap bit.  A straightforward way to
disable this is to set LD_HWCAP_MASK to 0x0 to clear hwcap bits.

On server systems where this would be used, this would have been done by
ldconfig and hence the lookup will not involve a full search every time,
just for situations where the library is not mapped into ld.so.cache.

Siddhesh