This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH 5/5] aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK


On Saturday 20 May 2017 03:42 AM, Szabolcs Nagy wrote:
> no oom on aarch64 does not mean there is no problem
> 
> LD_HWCAP_MASK changes the behaviour of _dl_init_path
> in elf/ld-load.c which we should understand before
> the patch is committed (because it implies the
> env var historically had different semantics than
> what we assumed).

Ahh, sorry, I just realized that we are talking about different things.
I thought you were objecting to including the patch until the OOM was fixed.

One may have additional search paths for every hwcap that is set by the
kernel, so if hwcap_cpuid is set, the linker (and ldconfig) ought to
search for /usr/lib/hwcap_cpuid for libraries to load as well.

This has an impact only if the target system is configured with
libraries in that hwcap path, e.g. if someone decides to have additional
libraries in /usr/lib/<hwcap feature> and that path gets searched only
if that hwcap feature is enabled.  This allows users to ship, say,
separate set of libraries for avx512 on x86_64 in /usr/lib/avx512_1
which gets searched before /usr/lib.

So masking out specific bits will disable searching of libraries in
those paths as well.  I hope that answers your question.

Siddhesh


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]