Comments on: Linkers part 1

Comment on Linkers part 1 by: Ian Lance Taylor

Mon, 05 Nov 2007 14:07:03 +0000

The goal is for the new linker to be part of the GNU binutils, which means that it will be GPLv3.

(I’ll add that I think that in practice there is very little difference between GPLv2 and GPLv3.)

Comment on Linkers part 1 by: avjo

Mon, 05 Nov 2007 07:30:37 +0000

Hi Ian,

This series is so educating and interesting ! Thank
you for that !

Just wondering here… will your new linker be GPLv2 or GPLv3 ?

~avjo

Comment on Linkers part 1 by: Ian Lance Taylor

Fri, 14 Sep 2007 04:30:36 +0000

Thanks for the note. There is a lot I don’t know about the history.

I didn’t make the comment about your book myself; it’s certainly the best description of linkers I know of. Still, unless I misremember, there are some recent important ideas which aren’t covered, such as ELF symbol versions, ELF (and Mach-O) symbol visibility, interposition with LD_PRELOAD and the like, TLS details. I don’t actually have a copy to hand, so I hope I am not misrepresenting it. These are not major ideas like incremental linking, but they are things which the relatively few people who work with linkers need to understand.

Comment on Linkers part 1 by: jrlevine

Thu, 13 Sep 2007 23:32:34 +0000

Nice series. Believe it or not, relocating loaders predate assemblers, with the first one in the late 1940s, and linking loaders aren’t much later. This technology goes way back.

Also, I was kind of surprised at the comment that my books was outdated. One of the reasons I wrote it was that linker technology changes so slowly. There hasn’t been an interesting new idea since incremental linkers about 20 years ago, knowledge of linkers has been mostly programmer folklore, so I figured I’d write it down so it’d be at last available somewhere. The descriptions of ELF, ECOFF, and they way they support dynamic linking are as far as I know still current, nothing’s changed since I wrote the book in 2000.

Comment on Linkers part 1 by: Mark J. Wielaard » Ian Lance Taylor’s Linker Notes

Fri, 31 Aug 2007 16:21:02 +0000

[…] Linkers part 1 - A Personal Introduction and A Technical Introduction. […]

Comment on Linkers part 1 by: christian schorn » Blog Archive » links for 2007-08-30

Thu, 30 Aug 2007 21:22:38 +0000

[…] Airs - Ian Lance Taylor » Linkers part 1 (tags: programming basics) […]

Comment on Linkers part 1 by: Ivan

Fri, 24 Aug 2007 04:41:55 +0000

Great Idea,

I look forward to reading these entries.

Thanks,
Ivan Novick
http://www.0×4849.net

Comment on Linkers part 1 by: Ian Lance Taylor

Fri, 24 Aug 2007 04:27:19 +0000

Thanks for the notes.

I tend to view template instantiation and link-time optimizations as separate from the linker proper. In implementations I know about, they are done before invoking the linker itself, or they are done via plugins which the linker invokes. That is, under the hood, there is still a classical linker.

But since there is interest, perhaps I will move on to those topics after covering the linker proper.

Comment on Linkers part 1 by: movement

Fri, 24 Aug 2007 03:41:20 +0000

Linkers and related topics such as runtime loaders and shared libraries
are a mystery at some level to most programmers, I find. It initially took
me a lot of time at staring at assembly output to work out link-time
relocations actually worked: both the Solaris linker and the GNU one are
pretty impenetrable if you’re just browsing. It’ll be very interesting to hear
some details from you on these topics.

Some related reading:

Sun’s Linkers and Libraries Guide
http://blogs.sun.com/rie/
http://blogs.sun.com/msw/
http://blogs.sun.com/ali/

John Levine’s old book Linkers and Loaders too. I didn’t get much out of
this book; unfortunately it was pretty outdated, and not very clearly put
together. I suspect the exercises would prove interesting to do though.

Comment on Linkers part 1 by: ncm

Fri, 24 Aug 2007 03:03:39 +0000

I too am looking forward to the rest of the series. It seems to me that it’s getting hard to make something recognizable, any more, as a classical linker, now that code generation and optimization are essential parts of the job.