RFC: Cygwin 64 bit?

Corinna Vinschen corinna-cygwin@cygwin.com
Mon Jun 27 07:26:00 GMT 2011

On Jun 27 06:49, Andy Koppe wrote:
> On 27 June 2011 04:08, JonY wrote:
> > I was thinking that 64bit Cygwin will be installed in a completely
> > separate directory so there is no chance in clobbering 32bit Cygwin
> > DLLs, like a parallel 1.5/1.7 install.
> A clean cut would be ideal, but I fear it would also greatly delay the
> project, because a large number of packages would need to be ported
> before the 64-bit distro would become viable for users. Supporting
> both 32-bit and 64-bit processes and having them interact seemlessly
> could avoid that.

Just as on 64 bit Linux.  And just as on Linux there will be
applications which won't be ported to 64 bit for quite some time.

AFAICS, the two DLLs can simply share all data and act as a unity.
There would be not much of a difference, except for running on a
different CPU, kind of.  To the best of my knowledge there's no
reason to keep 64 and 32 bit separate.

> This doesn't meant that Cygwin 2 (to coin a handle) still has to be
> installable on 32-bit systems, i.e. that 64-bit applications wouldn't
> still need 32-bit versions as well.

There's still 32 bit Cygwin.   I don't think we can neglect that.
And, as I said, there's no reason to do that.

> The situation is different with libraries, where the 32-bit versions
> would need to stick around as long as there are still 32-bit
> applications using them. Could this be handled with ABI bumps, so for
> example libncurses10 would remain 32-bit, but libncurses11 would be
> 64-bit? I think this would fit into the existing packaging
> infrastructure.

That's not an option, IMO.  What speaks against doing it the Linux way,
keeping 32 bit libs in {/usr}/lib and 64 bit libs in {/usr}/lib64?

In addition we will probably need a {/usr}/bin64, due to the $PATH
issue, and we probably have to talk about how mount behaves.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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