Running and debugging protected mode programs
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 Overview

 When Blinker creates a DOS extended program the format of the map file
 changes to reflect the different program structure. The segments are
 numbered sequentially starting at segment number 1, and many logical
 segments may be merged into a single physical segment.

 Running in a multitasking environment is probably the easiest method of
 debugging, particularly as the operating systems provide some sort of task
 isolation and crash protection so it is not necessary to reboot each time a
 protection exception occurs.

 When a protection exception or other protected mode error occurs, by default
 all the registers are dumped to the screen, along with the .EXE segment
 numbers associated with the segment registers. These segment numbers are the
 ones displayed in the MAP file created with the MAP S,A option, so can be
 used along with the offset registers IP, BX etc to quickly locate the
 location and cause of the error. For more details refer to Chapter 7 under
 .Debugging DOS extended programs..

 The DOS extender has to perform much less work in a DPMI environment than it
 does otherwise, so you are strongly advised to thoroughly test your programs
 in all the different environments in which it is intended to run. These
 should certainly include DPMI, VCPI and XMS. If they are only available in
 the same environment as DPMI, then DPMI support can be disabled by setting
 the BLINKER environment variable as described below.

 The actual mode in which the DOS extender is running can be tested using the
 DosGetHostMode() API function.

 Link script commands to control runtime

 Run time behaviour of a Blinker DOS extended program can be controlled at
 link time using various link script file commands. The current commands and
 their meanings are as follows (where there are choices the first setting
 shown is the default, and is in bold print):

    BLINKER EXTMEM BLOCK          Set extended memory block size
    BLINKER EXTMEM LIMIT nnnn     Set maximum extended memory to use
    BLINKER HOST DPMI ON | OFF    Enable / Disable DPMI host support
    BLINKER HOST VCPI ON | OFF    Enable / Disable VCPI host support
    BLINKER HOST XMS ON | OFF     Enable / Disable XMS host support