This is the mail archive of the cygwin-developers mailing list for the Cygwin project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Cygwin 64bit triplet

On Feb 20 21:14, Yaakov wrote:
> The bootstrap toolchain provided so far has used the x86_64-pc-cygwin
> triplet.  The problem is, now that we've managed to get far enough
> (before I threw a wrench into everything today :-)


Even with this change to the size of sszie_t, we have a *very* good
chance that our installations still work.  The reason is a curious
behaviour of the x86_64 CPU when using 32 bit register writes:

Every time, a 32 bit value is transfered into a register, the upper 32
bit are zeroed out:

   before: rax == 0x123456789abcdef

   movl #0x42, %eax

   after:  rax == 0x42

Consider that the first four arguments to a function are always stored
in registers ($rcx, $rdx, $r8, $r9), and consider that return values up
to 64 bit are returned in $rax.

==> There's a good chance we don't see a big difference.

I, just tested to run the "old" tcsh in mintty with the "new" Cygwin
DLL and everything still appears to work.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]