[Mingw-users] msys and \\?\ UNC paths

[Arnold H. <a.h...@b-...>]

I'm having trouble starting MSYS sh.exe from a process, and I think I've 
narrowed it down to our use of UNC paths (we use UNC paths to avoid 
dealing with the 255-path length limit on Windows)

  I seem unable to start the msys tools using \\?\ UNC paths (on WinXP 
SP3). I have installed the shell into C:\blexdev\msys\bin

Start > Run > C:\blexdev\msys\bin\sh.exe works fine, and so does typing 
"start C:\blexdev\msys\bin\sh.exe" in a cmd.exe window.

However, if I try to invoke the shell with

Start > Run > \\?\C:\blexdev\msys\bin\sh.exe
or
"start \\?\C:\blexdev\msys\bin\sh.exe "

I see a quick screen flashing by, which immediately disappears.

Starting notepad works fine this way, and "dir 
\\?\C:\blexdev\msys\bin\sh.exe" shows the shell, so the syntax looks ok 
to me. Does anyone have an idea where to start looking?

Arnold Hendriks