dll base address

Robert Collins robert.collins@itdomain.com.au
Sun Jun 10 18:20:00 GMT 2001


----- Original Message -----
From: "Christopher Faylor" <cgf@redhat.com>
To: <cygwin-developers@cygwin.com>
Sent: Monday, June 11, 2001 11:18 AM
Subject: Re: dll base address


> On Mon, Jun 11, 2001 at 10:52:41AM +1000, Robert Collins wrote:
> >----- Original Message -----
> >From: "Christopher Faylor" <cgf@redhat.com>
> >To: <cygwin-developers@cygwin.com>
> >Sent: Monday, June 11, 2001 2:08 AM
> >Subject: Re: dll base address
> >
> >
> >>On Sun, Jun 10, 2001 at 06:56:33PM +0400, egor duda wrote:
> >>>Sunday, 10 June, 2001 Christopher Faylor cgf@redhat.com wrote:
> >>>>>As you can see, cygwin1.dll has been loaded at 02561000.  It
seems
> >to me
> >>>>>that if __cygwin_user_data is a non-relocatble variable, that we
should
> >>>>>mark cygwin1.dll as non-relocatable.
> >>>>>
> >>>>>Thoughts?
> >>>
> ><snip>
> >>So, the DLL should be relocatable as long as it is consistently
being
> >>relocated to the same location.
> >>
> >>There is a lot more than just vtables that would need to be
addressed
> >>if we were to fix this.
> >
> >So for now, we should mark cygwin1.dll as non-relocatable.  How do we
> >do this for gcc/ld ?  MS LINK uses /FIXED, and I couldn't see a .def
> >instruction for it :[.
>
> For now, I think we should maintain the same practice as we have for
the
> last five years, i.e., we do nothing.
>
> AFAICT, this is all related to Paul Sokolovsky's auto-import patch to
> binutils/ld.  I do remember Paul talking about his techniques but I
> can't say for certain that they were actually submitted to the
binutils
> mailing list.  If they were submitted it was quite some time ago.

It's not related to the auto-import patch at all. It's purely a
relocation thing.

Trivial testcase: build a dll with normal ld witha base address of
0x610c0000. When linking against that .dll have that .dll listed before
cygwin1.dll in the imports section.

Run that program from bash. Watch cpu hit 100%. Run that program from
cmd.exe. Watch it work :].

<snip discussion predicated on incorrect cause of problem>

Rob
> cgf
>
> cgf
>



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