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Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
- From: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- To: sellcey at cavium dot com
- Cc: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>, adhemerval dot zanella at linaro dot org
- Date: Thu, 1 Jun 2017 10:59:05 +0530
- Subject: Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
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- Reply-to: siddhesh at sourceware dot org
On Wednesday 31 May 2017 01:53 AM, Steve Ellcey wrote:
> OK, I made a little progress. If I don't set LD_HWCAP_MASK then it
> seems to be treating it as 0, even though the default value is supposed
> to be HWCAP_IMPORTANT which gets set to HWCAP_CPUID. If I explicitly
> set LD_HWCAP_MASK to 0x800 then I get the correct heaviour and my
> program checks for CPUID. I am not sure why the default value for
> LD_HWCAP_MASK does not seem to be right.
I just realized what's going on; it is a bug in tunables. The
__tunables_set_val function returns without setting the value if the
value was not set by glibc.tune.hwcap_mask or LD_HWCAP_MASK, which is
wrong. It should return whatever is set in the tunable list.
I'll fix that and repost.