Date: Tue, 11 Feb 2020 09:18:47 -0800 From: John Baldwin <jhb@FreeBSD.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r357695 - in head: sys/kern sys/sys usr.bin/procstat Message-ID: <aa5c5bb8-63d8-a608-9579-af57b418b667@FreeBSD.org> In-Reply-To: <20200210191558.GX4808@kib.kiev.ua> References: <202002091210.019CAciS006085@repo.freebsd.org> <d04de408-be97-9405-b77d-d5f4cfdb248d@FreeBSD.org> <20200210191558.GX4808@kib.kiev.ua>
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On 2/10/20 11:15 AM, Konstantin Belousov wrote: > On Mon, Feb 10, 2020 at 10:11:43AM -0800, John Baldwin wrote: >> 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. > > So you would prefer to have me used AT_FLAGS for sigfastblock indicator ? > I am feeling uncomfortable doing that. > > My reasoning, to reformulate it from what I wrote in the commit message, > is to not pollute neither compilation nor ABI namespace for bsd-specific > flags. AT_FLAGS was not touched by anybody and I do not want to open > it for use, since ABI group my finally find some use for it. I would bet money the ABI group will never use AT_FLAGS since they haven't found a use yet. That said, adding a new auxv vector isn't the end of the world. I'll work on a patch to GDB when I get some spare time. -- John Baldwin
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