linux-kernel - Re: [RFC 0/2] __vdso

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Message-ID: <539DD26B.3060709@zytor.com>
Date:	Sun, 15 Jun 2014 10:05:47 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Rich Felker <dalias@...c.org>,
	Mikael Pettersson <mikpelinux@...il.com>
CC:	Andy Lutomirski <luto@...capital.net>, Russ Cox <rsc@...ang.org>,
	linux-api@...r.kernel.org, Ian Taylor <iant@...ang.org>,
	linux-kernel@...r.kernel.org, X86 ML <x86@...nel.org>
Subject: Re: [RFC 0/2] __vdso_findsym

On 06/15/2014 07:35 AM, Rich Felker wrote:
> 
> Arguably, it was a mistake for the kernel to expose a virtual ELF to
> begin with, and it should just have exposed a "lookup function by
> name" operation to begin with. Yes this can be done in userspace, but
> I see it more as a matter of "fixing a broken API design".
> 

What the fsck are you smoking?  There is immense value in providing a
stable and very well-defined data structure, which also happens to be
what dynamic linkers already want to consume.  Providing a helper for
crippled libc applications has potential value.  Shaving a few hundred
bytes off static applications is a very weak argument, simply because it
is such a small fraction of the enormous cost of a static application,
and static applications are problematic in a number of other ways,
especially the lack of ability to fix bugs.

Treating the kernel as an ersatz dynamic library for "static"
applications is kind of silly -- after all, why not provide an entire
libc in the vdso?  I have actually seen people advocate for doing that.

	-hpa

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