Re: bootstrap/3163

[Robert Lipe <robertlipe at usa dot net>]

The following reply was made to PR bootstrap/3163; it has been noted by GNATS.

From: Robert Lipe <robertlipe@usa.net>
To: gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, john@Calva.COM,
        gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org
Cc:  
Subject: Re: bootstrap/3163
Date: Wed, 13 Jun 2001 11:45:25 -0500

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=3163&database=gcc
 
                HP/UX allocates pages backward in memory. No OS has yet
 been
                observed
                to be so perverse as to leave unmapped space between
                consecutive calls
                to mmap. */
 
                Well, UnixWare 7.1.1 is that perverse system. It seems to
                leave
                one page between each mapping.
 
 This is actually documented behaviour.   From the mmap man page:
 
    References to pages in a mapped region which are beyond the
    page containing the end of a file will result in the delivery of a
    SIGBUS signal.
 
 It sounds like this test is looking for several undocumented 
 characteristics of mmap that just happen to be true on some systems
 and not a general case mmap.  Since the code provides a reasonable
 fallback, does this cause an actual problem or is it an observation
 that this test is failing becuase the OS doesn't satisfy the 
 characteristics wanted by this test?