svn commit: r357695 - in head: sys/kern sys/sys usr.bin/procstat

[John Baldwin]

On 2/9/20 4:10 AM, Konstantin Belousov wrote:
> Author: kib
> Date: Sun Feb  9 12:10:37 2020
> New Revision: 357695
> URL: https://svnweb.freebsd.org/changeset/base/357695
> 
> Log:
>   Add AT_BSDFLAGS auxv entry.
>   
>   The intent is to provide bsd-specific flags relevant to interpreter
>   and C runtime.  I did not want to reuse AT_FLAGS which is common ELF
>   auxv entry.
>   
>   Use bsdflags to report kernel support for sigfastblock(2).  This
>   allows rtld and libthr to safely infer the syscall presence without
>   SIGSYS.  The tunable kern.elf{32,64}.sigfastblock blocks reporting.
>   
>   Tested by:	pho
>   Disscussed with:	cem, emaste, jilles
>   Sponsored by:	The FreeBSD Foundation
>   Differential revision:	https://reviews.freebsd.org/D12773

I find adding a new auxv type curious.  The MIPS ABI doc says that
"bits under the 0xff000000 mask are reserved for system semantics".
The powerpc and x86-64 docs don't define any bits at all.  In
practice I think we are free to use AT_FLAGS however we wish as no
use cases of "standard" bits have arisen since AT_FLAGS was first
defined.

-- 
John Baldwin