Re: Accessing Wiggler from Linux GDB

["Aaron J. Grier" <aaron at frye dot com>]

On Thu, Dec 23, 1999 at 02:35:30PM -0600, Daris A Nevil wrote:

> I would certainly be interested in using a PowerPC wiggler directly
> from Linux.  I am currently using the EST "wiggler" and Windows based
> debugger on a custom MPC850 board running Linux.

Is this wiggler the same as the VisionProbe?

so lessee in summary... there's:

- public domain 2-chip interface
- public domain 5-chip interface (a few variants of this one)
- P&E ICD interface (is Pavel Pisa's PAL-design at [1] the same?)
- EST VisionProbe
- macgragor wiggler (similar or same as P&E?)

and that's just for CPU32.  Can any of these hardware interfaces be used
with coldfire or PPC?

- the 2-chip interface suffers from timing problems and cable lossage.
  It's supported under linux via Eric Norum / Chris John's driver.
- the 6-chip interface is better, but there's no way to recover from bus
  errors (you can't directly yank BERR down.)  It's also supported under
  linux via the Eric / Chris driver.
- the P&E ICD interface uses a PAL so cable runs can be longer, and the
  BERR line can be tweaked via host.  Pavel Pisa has drivers for CPU32
  and P&E at [1].  Unfortunately, these drivers (or combination of
  driver and patches to gdb) don't seem to handle BERR yanking.  [2]
- the EST visionprobe is proprietary, and has no linux drivers.  [3]
- I don't know anything about the macgragor wiggler...

I've been poking around with the Eric / Chris drivers and the U. of
Sask. 5-chip interface [4] trying to figure out why I'm getting bus
errors when setting or looking at SIM registers of my 68331.  I've been
slowly narrowing down the problem over the last few months and still
have a few questions.

Is there any way to get gdb to single step through instructions
_without_ writing breakpoints?  I have code loaded in ROM, and obviously
you can't insert BKPT instructions there.

[1] http://cmp.felk.cvut.cz/~pisa/m683xx/bdm_driver.html
[2] It's been about a month since I've worked with Pavel's code -- it
    may be worth looking at again.
[3] the visionXD debugger has been ported to linux, and EST will be
    happy to sell you a network CPU32 BDM interface.
[4] schematics are a good thing, and the Eric / Chris code is relatively
    clean and easy to follow.

-- 
  Aaron J. Grier   |   Frye Electronics, Tigard, OR   |   aaron@frye.com
  "The simplistic anthropomorphism which asserts that source code has a
   life separate from its creator or maintainer is the product of one
   too many viewings of Tron."  -- paraphrasing of anonymous post on /.

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