My view about RTEMS and GO32

[Joel Sherrill]

On Wed, 4 Mar 1998, Jose Carlos Oliveira wrote:

> After seeing the Go32 V1 code I noticed that the paging mechanism is
> based on exceptions. This approach means, that each time RTEMS uses for
> the first time a page, GO32 switches to Real Mode, pages the memory, and
> switch back to protected mode. Has I understand, this behavior is not
> consistent with a RTOS like RTEMS. 

The go32 BSP was never really intended for serious real-time use.  It was
a prototyping environment like the unix ports.  go32's interrupt overhead
is pretty bad also.

> Is this problem addressed in the new version ?

Yes in the sense that there is a "bare pc" BSP named pc386 which does not
use go32 at all.

> If in the new version the intention is to use the Version 2 (which uses
> a DPMI server), the problem is still present. Don't you think that is a
> good idea to have a small program in DOS that loads the RTEMS and after
> that is RTEMS that is responsible of configuring the system and
> switching to protected mode, maybe using the code for the FORCE386 BSP? 

No one has attempted to update the go32 BSP to v2.

> Maybe I'm behind scheduling and this approach is used in the new version

It could be but I do not know.

--joel
Joel Sherrill                    Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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