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Re: Wine MinGW system libraries

From Zebediah Figura <zfigura@codeweavers.com>
Newsgroups linux.debian.devel
Subject Re: Wine MinGW system libraries
Date 2021-09-08 17:50 +0200
Message-ID <CV7ZL-3Qu-3@gated-at.bofh.it> (permalink)
References (5 earlier) <CUN4Z-73U-5@gated-at.bofh.it> <CUQFA-UT-11@gated-at.bofh.it> <CUT0K-2dY-3@gated-at.bofh.it> <CV0vf-7wz-1@gated-at.bofh.it> <CV0Yi-7W8-11@gated-at.bofh.it>
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On 9/8/21 3:13 AM, Simon McVittie wrote:
> On Wed, 08 Sep 2021 at 07:31:59 +0000, Bastien ROUCARIES wrote:
>> Simon, do you think you could implement a version of libcapasule for PE object ?
> 
> Given that libcapsule is very glibc- and ELF-specific, doesn't work
> properly without new glibc feature work that isn't in Debian yet (I've
> lost track of whether/when it got merged upstream, it might be in 2.34)
> and wasn't written by me, the answer is likely to be no.
> 
> As far as I understand it, the PE loader used for Wine is part of Wine,
> so it has total control over the libraries that it loads and how it loads
> them. This means that if Wine developers (the experts on this codebase)
> have decided a libcapsule-like approach isn't feasible or isn't desirable,
> they are probably right.
> 
> More generally, if Wine developers wanted Wine's dependency libraries
> to be in one version of reality, and Windows DLLs to be in a different
> version of reality, then there's a straightforward way to do that:
> use ELF .so dependency libraries, like older versions of Wine did, and
> don't give them a representation in the PE layer. Presumably they have
> put in the work to move from ELF to PE dependency libraries because it
> has some compelling advantage, rather than creating work for themselves
> for no reason!

Yeah, basically :-)

The basic reason is that Wine is essentially trying to split itself into 
"PE" and "Unix" parts. The idea is that all of the "user" code is built 
in PE format, and only calls into unix code by making a sort of fake 
syscall. The "kernel" code is built in ELF format.

There are a few basic reasons for doing this:

* Many applications, mostly anti-cheat and anti-tamper engines, depend 
on our libraries actually being in PE format on disk, and matching that 
in memory. We used to have "fake" DLLs for this, but they weren't 
verisimilar enough.

* Some of the important hosts for Wine have dropped support for 32-bit 
libraries or are going to drop it. Mac is the obvious example here, but 
many commercial Linux distributions also want to drop support. By 
limiting the surface through which code can transition between PE and 
Unix code, it becomes feasible to do 32-to-64 translation, where 
previously this was quite infeasible.

* There's some demand for running Win32 debuggers under wine. These have 
always worked more than a little tenuously, but a couple of them are 
causing problems when they try to break in and unwind from Unix code. By 
acting like we're making actual syscalls, things work much better.

Of the several dozen modules we have that currently call into Unix 
libraries, about half of them aren't going to use PE dependencies. Most 
of these have already been fully split into PE and Unix parts, including 
things like the socket layer and winegstreamer. This raises the 
question: why not just call into Unix for the other half as well? There 
are a few reasons:

* Making fake syscalls is, like real syscalls, not cheap. It involves a 
full context switch into and out of Unix code.

* Making callbacks from Unix code is difficult, and not cheap either. 
For some libraries this doesn't matter, but for others it really does.

* Writing the wrappers between Unix and PE code involves some nontrivial 
work in itself. The smaller the interface is, the easier things are for us.

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Thread

Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-05 03:40 +0200
  Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-05 09:20 +0200
    Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-05 18:30 +0200
    Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 10:00 +0200
      Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-12 15:40 +0200
        Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 16:10 +0200
          Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-12 16:20 +0200
            Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 16:40 +0200
              Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-12 17:20 +0200
                Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 17:30 +0200
            Re: Wine MinGW system libraries Helmut Grohne <helmut@subdivi.de> - 2021-09-13 17:50 +0200
              Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-13 20:20 +0200
                Re: Wine MinGW system libraries Helmut Grohne <helmut@subdivi.de> - 2021-09-13 22:10 +0200
                Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-13 22:30 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-13 23:00 +0200
                Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-13 23:40 +0200
      Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-12 17:40 +0200
        Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 18:40 +0200
          Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-12 19:10 +0200
            Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-12 20:20 +0200
              Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-13 20:30 +0200
  Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-05 18:20 +0200
    Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-05 19:20 +0200
      Re: Wine MinGW system libraries Stephen Kitt <skitt@debian.org> - 2021-09-06 09:10 +0200
        Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-06 10:20 +0200
        Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-06 18:40 +0200
          Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-06 21:00 +0200
            Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-07 00:00 +0200
              Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-07 02:50 +0200
                Re: Wine MinGW system libraries "Bastien Roucariès" <roucaries.bastien@gmail.com> - 2021-09-07 12:40 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-07 17:50 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-07 19:30 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-07 20:20 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-07 23:20 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-08 01:50 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-08 09:50 +0200
                Re: Wine MinGW system libraries Simon McVittie <smcv@debian.org> - 2021-09-08 10:20 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-08 17:50 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-09 03:20 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-09 06:50 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-09 07:20 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-09 07:40 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-09 07:50 +0200
                Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2021-09-09 08:10 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-09 09:40 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-10 11:50 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-11 08:10 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-12 17:20 +0200
                Re: Wine MinGW system libraries Paul Wise <pabs@debian.org> - 2021-09-08 01:10 +0200
                Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-08 01:30 +0200
  Re: Wine MinGW system libraries Adrian Bunk <bunk@debian.org> - 2021-09-11 17:40 +0200
    Re: Wine MinGW system libraries Bastien ROUCARIES <roucaries.bastien@gmail.com> - 2021-09-11 20:10 +0200
  Re: Wine MinGW system libraries Zebediah Figura <zfigura@codeweavers.com> - 2022-04-17 02:30 +0200

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