MPC8xx binaries running on a MPC82xx board

MPC8xx binaries running on a MPC82xx board

[annamaya]

I was under the assumption that the MPC8xx core was
different from the MPC82xx core (the 603e?). But I was
surprised to find that the MPC8xx binaries were
running fine on a MPC82xx binaries, even if they were
dynamically linked and were linking to the MPC82xx
libraries. What's going on here? Can I just use the
8xx toolkit to work with the 82xx? There must be SOME
differences between these two architectures. Can
someone here explain this to me?


		
__________________________________ 
Do you Yahoo!? 
Check out the new Yahoo! Front Page. 
www.yahoo.com 
 

Re: MPC8xx binaries running on a MPC82xx board

[Kumar Gala]

One of the main issues that occurs when trying to run applications from=20=

8xx to 82xx is dealing with the difference in cache line size.  If code=20=

is written properly this difference will be invisible to the user.  It=20=

might be that 8xx code is not as optimal on 82xx because of it.

Also since you are going from 8xx -> 82xx your applications most likely=20=

are all integer code.  Going from 82xx -> 8xx may not be as successful.

- kumar

On Nov 9, 2004, at 10:37 AM, annamaya wrote:

> I was under the assumption that the MPC8xx core was
>  different from the MPC82xx core (the 603e?). But I was
>  surprised to find that the MPC8xx binaries were
>  running fine on a MPC82xx binaries, even if they were
>  dynamically linked and were linking to the MPC82xx
>  libraries. What's going on here? Can I just use the
>  8xx toolkit to work with the 82xx? There must be SOME
> differences between these two architectures. Can
>  someone here explain this to me?
>
>
>
> =A0=A0=A0=A0=A0=A0=A0 =A0=A0=A0=A0=A0=A0=A0
>  __________________________________
>  Do you Yahoo!?
> Check out the new Yahoo! Front Page.
> www.yahoo.com
>  =A0
>
> _______________________________________________
> Linuxppc-embedded mailing list
>  Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded

Re: MPC8xx binaries running on a MPC82xx board

[Dan Malek]

On Nov 9, 2004, at 11:37 AM, annamaya wrote:

> I was under the assumption that the MPC8xx core was
> different from the MPC82xx core (the 603e?).

Yes, it is different, but the instructions are all the same.

> ...... But I was
> surprised to find that the MPC8xx binaries were
> running fine on a MPC82xx binaries, even if they were
> dynamically linked and were linking to the MPC82xx
> libraries. What's going on here?

Partly luck, and partly that the instructions are the same.
The luck part is you aren't using floating point.  The 8xx
doesn't have hardware floating point, but the 82xx generated
code may have some instructions.  It also depends upon
the tools you are using.  If you were using different glibc
versions, your luck would have run out.

 From a user space application perspective, there are
exactly two differences between 8xx and 82xx.  One is
floating point and the other is cache line size.  The 8xx
software will run fine on the 82xx, but 82xx may not
work properly on 8xx.

> ...... Can I just use the
> 8xx toolkit to work with the 82xx?

An 8xx toolkit will always work on 82xx, but depending
upon the way it was built, you will not get the maximum
performance of the 82xx.  Some tool vendors generate
toolkits (and libraries) specifically for the 8xx, where the
floating point is all emulated in software.  If you were looking
for floating point performance, you would be very disappointed
with this on the 82xx.

> ....... There must be SOME
> differences between these two architectures. Can
> someone here explain this to me?

There are lots of differences in the kernel programming
model, but only the two I mentioned for user space
applications.  In fact, across the entire PowerPC architecture
you will only see floating point, Altivec, SPE, and some
cache line operation/implementation differences at
the user level.  Depending upon your software
requirements and implementation, you are likely
able to run many of the same binaries across all
of the PowerPC cores.

I guess we are rewriting the archives now? :-)


	-- Dan

Re: MPC8xx binaries running on a MPC82xx board

[annamaya]

Dan,

I appreciate your reply. And I apologize for asking
you again if this was in the archives. BTW, are the
archives back up again somewhere, after the whole
linuxppc embedded mailing server crash?

You said that there were a lot of kernel level
differences that you mentioned about between the 8xx
and 82xx. Can you be more specific and give me some
examples? I will be mostly working with kernel space
code for the 82xx and I would like to understand the
differences here.

Thanks again.

--- Dan Malek <dan@embeddededge.com> wrote:

> 
> On Nov 9, 2004, at 11:37 AM, annamaya wrote:
> 
> > I was under the assumption that the MPC8xx core
> was
> > different from the MPC82xx core (the 603e?).
> 
> Yes, it is different, but the instructions are all
> the same.
> 
> > ...... But I was
> > surprised to find that the MPC8xx binaries were
> > running fine on a MPC82xx binaries, even if they
> were
> > dynamically linked and were linking to the MPC82xx
> > libraries. What's going on here?
> 
> Partly luck, and partly that the instructions are
> the same.
> The luck part is you aren't using floating point. 
> The 8xx
> doesn't have hardware floating point, but the 82xx
> generated
> code may have some instructions.  It also depends
> upon
> the tools you are using.  If you were using
> different glibc
> versions, your luck would have run out.
> 
>  From a user space application perspective, there
> are
> exactly two differences between 8xx and 82xx.  One
> is
> floating point and the other is cache line size. 
> The 8xx
> software will run fine on the 82xx, but 82xx may not
> work properly on 8xx.
> 
> > ...... Can I just use the
> > 8xx toolkit to work with the 82xx?
> 
> An 8xx toolkit will always work on 82xx, but
> depending
> upon the way it was built, you will not get the
> maximum
> performance of the 82xx.  Some tool vendors generate
> toolkits (and libraries) specifically for the 8xx,
> where the
> floating point is all emulated in software.  If you
> were looking
> for floating point performance, you would be very
> disappointed
> with this on the 82xx.
> 
> > ....... There must be SOME
> > differences between these two architectures. Can
> > someone here explain this to me?
> 
> There are lots of differences in the kernel
> programming
> model, but only the two I mentioned for user space
> applications.  In fact, across the entire PowerPC
> architecture
> you will only see floating point, Altivec, SPE, and
> some
> cache line operation/implementation differences at
> the user level.  Depending upon your software
> requirements and implementation, you are likely
> able to run many of the same binaries across all
> of the PowerPC cores.
> 
> I guess we are rewriting the archives now? :-)
> 
> 
> 	-- Dan
> 
> 



		
__________________________________ 
Do you Yahoo!? 
Check out the new Yahoo! Front Page. 
www.yahoo.com 
 

Re: MPC8xx binaries running on a MPC82xx board

[Dan Malek]

On Nov 9, 2004, at 12:30 PM, annamaya wrote:

> I appreciate your reply. And I apologize for asking
> you again if this was in the archives.

It was a joke.  I would have said "read the archives"
if they were around. :-)  Now we have some of the
info in the "new" archives.

> ......Can you be more specific and give me some
> examples?

This isn't the place to discuss that.  Grab the manuals,
read them, you will see the differences.


	-- Dan

Re: MPC8xx binaries running on a MPC82xx board

[annamaya]

Thanks much for the input. I have been reading the
manual for the MPC82xx and I will continue to do so
till I understand the processor better.

--- Dan Malek <dan@embeddededge.com> wrote:

> 
> On Nov 9, 2004, at 12:30 PM, annamaya wrote:
> 
> > I appreciate your reply. And I apologize for
> asking
> > you again if this was in the archives.
> 
> It was a joke.  I would have said "read the
> archives"
> if they were around. :-)  Now we have some of the
> info in the "new" archives.
> 
> > ......Can you be more specific and give me some
> > examples?
> 
> This isn't the place to discuss that.  Grab the
> manuals,
> read them, you will see the differences.
> 
> 
> 	-- Dan
> 
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com