Would a JTAG port help with sun4d SMP work?

Would a JTAG port help with sun4d SMP work?

[Adam Hunt]

I was just sitting here at 5:56am PST looking around my bedroom when
my SPARCserver 1000E caught my eye.  I got it from a guy who's wife
was making him clean out the garage.  I've never had any real Sun
equipment (I did have a little MicroSPARC box that was made by someone
other then Sun but I never got the chance to fire it up).  I'd really
like to get this unit up and running with all of it's processors fired
up.  For whatever reason I decided to pull it apart.  After I removed
the front covers I found what I assume is an EEPROM reset button and a
DB25 connector on the control board (part 501-1979).   Wondering what
the connector could be for I searched the web for it's board label
(J0101) and found that it is a JTAG port.

What does this have to do with all of you?  Well I know that there are
a couple of people (William Lee Irwin and C. Newport) that were
working on getting the sun4d line to boot in SMP mode and I thought
that access to the main JTAG might just help with that.

I appologize for the noise if everyone already knows the above
information or if it is of no help.

--adam

Re: Would a JTAG port help with sun4d SMP work?

[C.Newport]

On Wednesday 27 October 2004 2:08 pm, Adam Hunt wrote:
> After I removed
> the front covers I found what I assume is an EEPROM reset button and a
> DB25 connector on the control board (part 501-1979).   Wondering what
> the connector could be for I searched the web for it's board label
> (J0101) and found that it is a JTAG port.

Thanks for the reminder. 
I did look into this a while ago and it did not appear to be of much 
relevance. Maybe wli will find otherwise when he receives his machine
and starts work debugging the known issues.

Re: Would a JTAG port help with sun4d SMP work?

[William Lee Irwin III]

On Wed, Oct 27, 2004 at 01:08:06AM -1200, Adam Hunt wrote:
> I was just sitting here at 5:56am PST looking around my bedroom when
> my SPARCserver 1000E caught my eye.  I got it from a guy who's wife
> was making him clean out the garage.  I've never had any real Sun
> equipment (I did have a little MicroSPARC box that was made by someone
> other then Sun but I never got the chance to fire it up).  I'd really
> like to get this unit up and running with all of it's processors fired
> up.  For whatever reason I decided to pull it apart.  After I removed
> the front covers I found what I assume is an EEPROM reset button and a
> DB25 connector on the control board (part 501-1979).   Wondering what
> the connector could be for I searched the web for it's board label
> (J0101) and found that it is a JTAG port.
> What does this have to do with all of you?  Well I know that there are
> a couple of people (William Lee Irwin and C. Newport) that were
> working on getting the sun4d line to boot in SMP mode and I thought
> that access to the main JTAG might just help with that.
> I appologize for the noise if everyone already knows the above
> information or if it is of no help.

The use of the JTAG would allow rather immediate and enormous advances
if we had any notion of how to use it. I suspect this is not an entirely
uncommon state of affairs, as I've heard that e.g. Exy00's all have open
JTAG ports, none of which we have any notion of how to use AFAIK.

-- wli

Re: Would a JTAG port help with sun4d SMP work?

[David S. Miller]

On Wed, 27 Oct 2004 10:56:12 -0700
William Lee Irwin III <wli@holomorphy.com> wrote:

> The use of the JTAG would allow rather immediate and enormous advances
> if we had any notion of how to use it. I suspect this is not an entirely
> uncommon state of affairs, as I've heard that e.g. Exy00's all have open
> JTAG ports, none of which we have any notion of how to use AFAIK.

THe Ex000 JTAG's are driven by the registers mapped by
the arch/sparc64/kernel/central.c driver code.

The specific registers are defined in asm-sparc64/fhc.h

But that's where the information stops, sorry :-)

One thing I do remember is that only one board can be
declared as the JTAG master and do chain scans.

Each board type (CPU+MEM, SBUS, PCI, etc.) has different
layout and meanings of the scan chains.

You actually have to use this stuff to hotplug boards.  OBP
is supposed to take care of it via special OBP prom calls but
some of those are buggy so you have to jumpstart the board
by hand using JTAG commands.

I would not be surprised if the sun4d JTAG programming is similar.
The UltraSPARC main bus, interrupt, streaming cache, and IOMMU
architecture is largely derived from the sun4d stuff.