[PATCH] Cygwin: mmap: use 64K pages for bookkeeping

[Takashi Yano]

On Mon, 13 Jan 2025 12:04:36 +0100
Corinna Vinschen wrote:
> On Jan 10 16:18, Ken Brown wrote:
> > Patch attached.
> > 
> > This turned out to be completely trivial, unless I'm missing something. I
> > tested it with several programs that use mmap, and it seems OK.
> > 
> > Ken
> 
> > From 654e5c83da077b67683a1aefd79a414ed6067e51 Mon Sep 17 00:00:00 2001
> > From: Ken Brown <kbrown@cornell.edu>
> > Date: Fri, 10 Jan 2025 14:39:46 -0500
> > Subject: [PATCH] Cygwin: mmap: use 64K pages for bookkeeping
> > 
> > It was convenient to use pages of size 4K (Windows page size) for
> > bookkeeping when we were using filler pages.  But all references to
> > filler pages were removed in commit ceda26c9d35b ("Cygwin: mmap:
> > remove __PROT_FILLER and the associated methods"), so this is no
> > longer necessary.  Switch to using pages of size 64K (Windows
> > allocation granularity) for everything.
> > 
> > Signed-off-by: Ken Brown <kbrown@cornell.edu>
> > ---
> >  winsup/cygwin/mm/mmap.cc | 29 ++++++++++++++++-------------
> >  1 file changed, 16 insertions(+), 13 deletions(-)
> 
> Sounds good to me.

With this patch, gdb no longer works in my environment:

$ gdb
Pre-boot error; key: system-error, args: ("load-thunk-from-memory" "~A" ("Invalid argument") (22))

Fatal signal: Aborted
----- Backtrace -----
---------------------
A fatal error internal to GDB has been detected, further
debugging is not possible.  GDB will now terminate.

This is a bug, please report it.  For instructions, see:
<https://www.gnu.org/software/gdb/bugs/>.

Abort
$

Any idea?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>