linux-kernel - Re: vdso feature requests from the Go people

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Message-ID: <539A8E89.5000602@zytor.com>
Date:	Thu, 12 Jun 2014 22:39:21 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	X86 ML <x86@...nel.org>, Russ Cox <rsc@...ang.org>,
	Ian Taylor <iant@...ang.org>
Subject: Re: vdso feature requests from the Go people

On 06/12/2014 10:23 PM, Andy Lutomirski wrote:
> 
> As far as I know, there's no reliable way to just read the dynsym
> table -- the thing doesn't have a specified length, which is what
> broke Go in the first place.
> 

Ah yes, you're right.

>
> Parsing the ELF dynamic tables is kind of annoyingly complicated, and
> understanding the format is a real PITA -- the documentation I've been
> able to find is outright terrible.
> 

Yes... not entirely clear that putting it in the vdso is a net win,
though.  There are some people who would like to put a significant chunk
of libc in the vdso, and it just doesn't seem like a good idea.

An index table is somewhat more reasonable, but (a) not backwards
compatible (so wouldn't work with older kernels) and (b) has shades of
Windows...

	-hpa


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