[Ref: pasc-1003.1b-04] Topic: mmap

Defect Report concerning: IEEE Std. 1003.1b-1993, ISO/IEC 9945-1:1990 AMD 1 - Realtime
Clause: 12.2.1
PASC Interpretation Ref: pasc-1003.1b-04
Topic: mmap

This is an unapproved interpretation of PASC 1003.1b-1993, ISO/IEC 9945-1:1990 AMD 1 - Realtime.

Use of the information contained in this unapproved document is at your own risk.

Last update: 23 March,1998

                                                                1003.1b-93 #4

 _____________________________________________________________________________

	Interpretation Number:  (to be assigned by the IEEE)
        Topic:                  mmap
        Relevant Sections:      12.2.1
        Classification:         (to be assigned)



Interpretation Request: (Defect Report)
-----------------------

Date: Fri, 28 Oct 1994 09:16:14 -0500
From: willcox@urbana.mcd.mot.com (David A. Willcox)

I would like to request a formal interpretation on IEEE Std
1003.1b-1993, Real Time Extensions.

IEEE Std 1003.1-1990 defines file times (access time and modification
time), and specifies in detail how functions in that standard effect the
file times.

IEEE Std 1003.1b-1993 adds the mmap() function (12.2.1) as a completely
new way to access a regular file.  However, It does not seem to specify
how accesses to a file via mmap() affect the file times.

To be specific, when shall, and when may, the implementation mark
st_atime and st_mtime for update in each of the following cases:

(1) mmap() is called with PROT_READ.
(2) mmap() is called with MAP_SHARED and PROT_WRITE.
(3) Application modifies a page previous mapped with MAP_SHARED, PROT_WRITE.
(4) Application references a page mapped MAP_PRIVATE that has
    not been modified by the process.  (Keep in mind that the process
    might be seeing data that has changed since the mmap().)
(5) Application modifies a page mapped MAP_PRIVATE, PROT_WRITE.
(6) Application references a page mapped MAP_PRIVATE that was
    previously modified by the process.
(7) msync() (12.2.4) is called on pages mapped with mmap().


IEEE Interpretation for 1003.1b-1993
------------------------------------
The standard is silent on this matter.  The committee notes that this is
inconsistent with page 27 line 626 which states generally that it should
specified and this matter is being referred to the sponsor for consideration.

Rationale
----------

None.