On Jan 25, 8:53 am, "Alec Mihailovs" <a...@mihailovs.com> wrote:
> From: "mabshoff" <mabsh...@googlemail.com>
>
> > There shouldn't be two cygwin.dlls on the same computer.
> > No, this does not apply since first cygwin1.dll in %PATH% or CWD will
> > be the one used if no DLL has been loaded into RAM. You cannot run two
> > different Cygwin instances at the same time and expect them to work.
>
> The problems usually occur when a "wrong" cygwin's dll is loaded. It was a
> recurring topic on the cygwin's mailing list for several years (I don't
> subscribe to it now.) That's why the best way for an application to work
> used to be to include it in the cygwin distribution. I don't use cygwin now,
> so that may be changed though.
Yes, different cygwin1.dlls are still some times incompatible and that
can lead to subtle and even not so subtle issues. But I would expect
many Sage on Windows users to not have Cygwin installed at all, so in
that case this is a non-issue. The problem with installing a binary
Sage into a working Cygwin install is mainly that one needs to rebase
all DLLs and Python extensions since their location in RAM are hard
coded into the libraries and the location of various system libraries
with Cygwin change from release to release. Since many people are
usually unable to follow simple instructions, i.e. how to install 7zip
and unpack the VMWare image defeated many students from installing the
VMWare image when it was 7zip compressed, I am not too confident that
posting an ash script that rebases all of Sage from *outside* Cygwin
and has to be run from cmd.exe with an absolute path to Cygwin is
going to cut it. And that script has to be run multiple times when
building Sage and even *after every time* you build/update even a
single extension to make 100% sure that dlopen'ed extensions work.
That is the specific reason that building Sage on Cygwin sucks more
than on any other platform, aside from the terrible performance of
shell scripts due to the pathetic performance of fork() on Cygwin.
> Alec
Cheers,
Michael
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