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Re: Cygwin 64bit triplet
- From: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- To: cygwin-developers at cygwin dot com
- Date: Thu, 21 Feb 2013 13:39:48 +0100
- Subject: Re: Cygwin 64bit triplet
- References: <20130220211406.253d7332@YAAKOV04>
- Reply-to: cygwin-developers at cygwin dot com
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 :-)
Btw!
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
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
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