[OT?] rebasing cygwin, was: cygwin/xfree86/emacs problems after upgrading

[OT?] rebasing cygwin, was: cygwin/xfree86/emacs problems after upgrading

[Thomas L Roche]

Al Williams 13 Feb 2004 13:18:32 -0800
> I was having this problem. Rebasing the Cygwin DLLs seems to have
> cleared it up. Install rebase using setup and then exit all Cygwin
> stuff (including httpd, etc.). Then open a plain shell (not an xterm)
> and enter:

> rebaseall -v

Could you give me, or pass pointers to, a bit more information about
rebase? I'm asking because I can't find much online, except

http://sources.redhat.com/ml/cygwin-announce/2003-09/msg00039.html
> <WARNING>
> It is *strongly* recommended that users only use rebaseall unless
> they *really* know what they are doing or are instructed by one of
> the Cygwin developers.
> </WARNING>

which is pretty scary. It continues,

> The Cygwin rebase package contains two utilities, rebase and
> rebaseall. The first utility is modeled after Microsoft's SDK
> rebase:

> http://msdn.microsoft.com/library/en-us/tools/perfutil_2z39.asp

which 404s.

Re: [OT?] rebasing cygwin, was: cygwin/xfree86/emacs problems after upgrading

[Al Williams]

Thomas L Roche <tlroche@us.ibm.com> wrote in message news:<mailman.2448.1076893498.928.help-gnu-emacs@gnu.org>...
> Could you give me, or pass pointers to, a bit more information about
> rebase? I'm asking because I can't find much online, except

Well, actually it did not completely eliminate the problem although it
did reduce its frequency significantly (once or twice a day instead of
five or six times an hour).

Each DLL has a preferred load address. If it can be loaded at that
address, fine. If not, Windows will put it at a different address.
Apparently (and I don't know this for sure) the Cygwin stuff assumes
all DLLs will be at the same address in each process space (as would
always be the case in Win98, for example). So if DLLs conflict and are
loaded in different order, it is possible for process A to have DLLx
at addresss Z and process B has DLLy at the same address and Cygwin
apparently detects this and stops.

Rebasing moves the DLL load addresses to make this less likely. 

If you google on:

rebaseall cygwin

You'll see this is a common issue with certain packages. I don't think
it will really hurt anything. If you are really worried, copy all the
DLL files under c:\cygwin (or whatever your CYGROOT is) before you
start.

Al Williams
http://www.al-williams.com