Etch on Windows 95 -- Release Notes
Etch was developed and tested primarily on the Windows NT platform
(NT version 4.0), but we recently began an effort to port Etch to
the Windows 95 platform. This document describes the places that
we've found where Etch behavior differs on Windows 95 from its
behavior on Windows NT.
Environment
and Installation Issues
- The Win95 command shell, by default, does not have enough
environment space to allow the Etch installation scripts
to run properly. You will see the error message "Out
of environment space" unless you change the default
amount of environment space, by using the
"Properties" menu on the MS-DOS icon. We recommend
you set it to 4096.
- In WinNT, when an etched process generates a GPF, the
process dies and the operating system returns control the
tool script. In Win95, a GPF sometimes causes a blue
screen to appear, and in this case the tool script
doesn't get back control. A workaround is to find the
MS-DOS window that has the title "dllwalk" or
"etch" and close that window. This will kill
the tool script. Note that this will cause Visual Etch to
emit a warning message about the tool script dying
prematurely.
- Occasionally, when an etched application dies on Win95,
the operating system fails to give up the lock on the
etched application .exe file (e.g. forloop-etch.exe).
This causes Visual Etch to fail when it tries to delete
this file (e.g. when it tries to create a new
forloop.exe). The only known workaround at this time is
to reboot the computer.
- The device drivers for the hardware performance counters,
and all tools that use them, don't work on Win95 on the
P6 platform.
- The cgprof browser emacs-lisp code doesn't work on Win95.
- On WinNT, Visual Etch embeds the USERNAME environment
variable in the path when it creates the default project.
On Win95, the USERNAME environment variable is not set, so
Visual Etch uses the string "me" instead.
- setupreg.exe built on NT will not work on Win95 because of differences
in registry implementations between the two operating systems.
Although the source is the same, a version of setupreg.exe has to
be built on a Win95 box for it to work on Win95 boxes.
DLL Issues
- The upper region of the Win95 address space is shared
amongst all applications. Dll's that are loaded in this
region should not be etched or patched, because this could affect
other applications running on the system. The list of
Dlls in this category (there are about 20) can be
found in params.mdb. We maintain separate sets of defaults
for Win95 and NT in the params.mdb database.
- Another problematic DLL is mpr.dll (a Windows networking
DLL). When etched, it causes Word95 to hang when opening
files. And when only patched, it causes Word95 to perform
an illegal instruction on exit. For these reasons,
mpr.dll is neither etched nor patched with any
application by default.
- There are a small number of other DLLs that fail to Etch
on Win95 but Etch without problems on WinNT. Of the
common DLLs, shell32.dll and msshrui.dll fall into this
category.
Tool Issues
The following tools do not work under Win95 because they require driver
support for the P6 hardware performance counters.
Measure Optimized Performance
Dll Instruction Counts
Instrumentation Coverage (Approximate - fast)
Hardware Performance Counters