Getting started with ARM processors - recommendations

On 29/10/10 22:59, rickman wrote:
> On Oct 29, 4:07 am, David Brown<da...@westcontrol.removethisbit.com>
> wrote:
>> On 29/10/2010 02:36, hamilton wrote:
>>
>>> On 10/28/2010 3:18 PM, Ulf Samuelsson wrote:
>>>> The AVR32 is more in the Cortex-M4 class, than the M3.
>>
>>> How does the AVR32 compare to the MIPS processors ??
>>
>> It compares with difficulty.
>>
>> MIPS is a family of licensable cores covering a huge spread.  The
>> microMIPS cores will be probably be smaller and lower power than an
>> AVR32 (though it will depend on the implementation), while the biggest
>> cores are orders of magnitude faster.  "MIPS" is more like "ARM" in this
>> respect.
>
> I guess you can't knock the MIPS parts for being a poor step child
> like the AVR32.  It may not be available from more than one maker as a

I don't know quite what you mean about the AVR32 being a "poor step 
child" - it's an independent modern 32-bit processor architecture with 
all the advantages and disadvantages that brings.

But MIPS has been around for decades - it's older than ARM, and 
certainly much more established than the modern popular ARM cores.  MIPS 
also have more experience at the higher end - they had 64-bit cores long 
before the amd64 architecture (or even Intel's disastrous IA-64), and 
SMP is standard stuff for MIPS.  But they haven't had so much at the low 
end until recently - the microMIPS extensions are quite new.  And they 
have always targeted a few big customers rather than being used by the 
"little people".

> standard part, it does have a huge base of users, etc.  So it is not
> likely to go away... at least not as a core.  Has Microchip been
> selling these chips in high enough volume to assure that they will
> continue to make them for years to come?  That would be my biggest
> concern at this point.
>

MIPS is a core that will never go away - it is far too established for 
that.  People who want a CPU core for their chips that will be used for 
the next 20 years pick either MIPS or PPC cores.

I have no idea how popular the PIC32 is.  Microchip's handling of 
"their" PIC32 compiler puts me off it.

> The other 32 bit chips with a sole source core may have commitment
> from their makers.  Renesas for example, will not likely drop their
> offerings.  But Toshiba has at least put one foot on the ARM
> bandwagon.  I can't imagine they will continue to develop and promote
> both product lines indefinitely, likewise for Atmel, regardless of
> what some will tell you.
>
> So if the PIC32 parts don't sell well, how much pain is Microchip
> willing to take before they drop the line???  I guess if they are
> licensing the M14K core, they are at least going to continue with this
> part for another five years.
>
>
>> The most power-efficient MIPS core is probably the M14Kc at 90nm, and if
>> you accept the raw figures from MIPS website it has a core power of 0.08
>> mW/mHz, runs at 200 MHz and does 1.5 DMIPS/MHz.
>>
>> If you look at the list of MIPS licensees, you will not have heard of
>> most of the companies.  And of those you have heard of, you know most of
>> them as end-product manufacturers (such as Cisco).  There are familiar
>> names on the list, such as Texas Instruments, but you won't find a
>> mention of MIPS on their website - they have it available as a core for
>> their ASIC customers.  MIPS processors are one of the most widely used
>> architectures (I'd love to see figures comparing the numbers of MIPS,
>> ARM and x86 processors in use).  But they are also mostly invisible
>> unless you are in the market for at least hundreds of thousands of
>> devices at a time, or are involved in particular market segments
>> (high-end networking and set-top boxes are a couple of examples).
>>
>> The only MIPS devices that are easily available in the mass market are
>> the Microchip PIC32 devices.  AFAIK, they use the M4K - a somewhat
>> larger and older core than the above-mentioned M14Kc.  How it compares
>> in power to the AVR32 devices, I don't know.
>
> I'm sure they are working to keep up with anything the ARM camp throws
> at them.  If they are going in ASICs, I expect they aren't just being
> selected because of the existing code base.  They also need to be
> technically competitive.
>

David Brown wrote:

> But MIPS has been around for decades - it's older than ARM, and
> certainly much more established than the modern popular ARM cores.  

And getting a lot of use in China as a mainstream processor -- not so much 
embedded or microcontroller.  See Dragon Chip.

	Mel.

On 10/30/2010 8:35 AM, Mel wrote:
>
> And getting a lot of use in China as a mainstream processor -- not so much
> embedded or microcontroller.  See Dragon Chip.
>
> 	Mel.

Google found all sorts of interesting things.


1GHz Chinese Dragon chip Comparable to 2GHz Pentium 4

http://www.itechnews.net/2006/03/31/1ghz-chinese-dragon-chip-comparable-to-2ghz-pentium-4/

On Oct 30, 8:58=A0am, David Brown
<david.br...@removethisbit.hesbynett.no> wrote:
> On 29/10/10 22:59, rickman wrote:
>
>
>
> > On Oct 29, 4:07 am, David Brown<da...@westcontrol.removethisbit.com>
> > wrote:
> >> On 29/10/2010 02:36, hamilton wrote:
>
> >>> On 10/28/2010 3:18 PM, Ulf Samuelsson wrote:
> >>>> The AVR32 is more in the Cortex-M4 class, than the M3.
>
> >>> How does the AVR32 compare to the MIPS processors ??
>
> >> It compares with difficulty.
>
> >> MIPS is a family of licensable cores covering a huge spread. =A0The
> >> microMIPS cores will be probably be smaller and lower power than an
> >> AVR32 (though it will depend on the implementation), while the biggest
> >> cores are orders of magnitude faster. =A0"MIPS" is more like "ARM" in =
this
> >> respect.
>
> > I guess you can't knock the MIPS parts for being a poor step child
> > like the AVR32. =A0It may not be available from more than one maker as =
a
>
> I don't know quite what you mean about the AVR32 being a "poor step
> child" - it's an independent modern 32-bit processor architecture with
> all the advantages and disadvantages that brings.

Yes, poor step child as in not getting all the same stuff that the
others get... like a huge following, open source tools (not sure about
that one), but the main thing is that it is 100% sole sourced.  If
Atmel doesn't make the flavor you need, go pound sand.  With ARM you
can go to another vendor to find just the mix that suits your app
best.


> But MIPS has been around for decades - it's older than ARM, and
> certainly much more established than the modern popular ARM cores. =A0MIP=
S
> also have more experience at the higher end - they had 64-bit cores long
> before the amd64 architecture (or even Intel's disastrous IA-64), and
> SMP is standard stuff for MIPS. =A0But they haven't had so much at the lo=
w
> end until recently - the microMIPS extensions are quite new. =A0And they
> have always targeted a few big customers rather than being used by the
> "little people".

I got no problem with MIPS.  But if there is only one supplier of a
MIPS MCU, it has the same limitation that AVR32 has.


> > standard part, it does have a huge base of users, etc. =A0So it is not
> > likely to go away... at least not as a core. =A0Has Microchip been
> > selling these chips in high enough volume to assure that they will
> > continue to make them for years to come? =A0That would be my biggest
> > concern at this point.
>
> MIPS is a core that will never go away - it is far too established for
> that. =A0People who want a CPU core for their chips that will be used for
> the next 20 years pick either MIPS or PPC cores.

Isn't that what I said, it is not likely to go away... as a core.  As
an MCU it may or may not make the cut.  Why do you think ARM is not
good for the next 20 years?  They are running away with the MCU market
at this point.


Rick

David Brown wrote:

[...]

>MIPS is a core that will never go away - it is far too established for 
>that.  People who want a CPU core for their chips that will be used for 
>the next 20 years pick either MIPS or PPC cores.

M68K should be mentioned.

Oliver
-- 
Oliver Betz, Munich
despammed.com is broken, use Reply-To:

On 2010-10-30, Mel <mwilson@the-wire.com> wrote:
> David Brown wrote:
>
>> But MIPS has been around for decades - it's older than ARM, and
>> certainly much more established than the modern popular ARM cores.  
>
> And getting a lot of use in China as a mainstream processor -- not so much 
> embedded or microcontroller.  See Dragon Chip.
>

Before these and similar processors are used in products, what tests do
companies perform to make sure that some nasty logic surprises have not
been left in them ?

I have known for some time about the possibility of hardware based spying
instead of software based spying, but have not really thought about it
been mainstream yet.

However, Scientific American ran a article on this a couple of months ago
and it made me think about how widespread concerns about this must be if
it's considered newsworthy enough for a international science magazine to
run a full article on it.

In other words, is it possible there are some nasty surprises just waiting
for us in the existing hardware on our desks, in our server rooms and in
our mobile devices ?

Simon.

-- 
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world

On 2010-10-31, Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> wrote:
>
> In other words, is it possible there are some nasty surprises just waiting
> for us in the existing hardware on our desks, in our server rooms and in
> our mobile devices ?
>

I notice I wrongly cut out embedded systems from that sentence, which is
annoying given that this _is_ comp.arch.embedded. :-)

Given the traditional lax security found on many network connected embedded
systems, the possibility of hardware surprises in those systems is of course
a major concern.

Simon.

-- 
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world

Simon Clubley <clubley@remove_me.eisner.decus.org-earth.ufp> wrote:

> In other words, is it possible there are some nasty surprises just waiting
> for us in the existing hardware on our desks, in our server rooms and in
> our mobile devices ?

Of course, but that's not exclusive to China.

-a

Simon Clubley wrote:

[%X]

> Before these and similar processors are used in products, what tests do
> companies perform to make sure that some nasty logic surprises have not
> been left in them ?

Apart from incorrect maths functions and inverted logical operations?
 
> I have known for some time about the possibility of hardware based spying
> instead of software based spying, but have not really thought about it
> been mainstream yet.

Whether or not it is mainstream yet might depend on the numbers and types of 
devices we are speaking about.
 
> However, Scientific American ran a article on this a couple of months ago
> and it made me think about how widespread concerns about this must be if
> it's considered newsworthy enough for a international science magazine to
> run a full article on it.
> 
> In other words, is it possible there are some nasty surprises just waiting
> for us in the existing hardware on our desks, in our server rooms and in
> our mobile devices ?

The question would be "how many organisations need to be either so lax or 
complicit in ensuring that those who wanted to steal information could 
succeed?".

In dealing with components from suppliers I obtain certificates of 
conformity to the data-sheet. With more complex logic devices, I run tests 
on a few sample components to the extent of satisfying myself that the 
devices are as described in the data-sheet. Not having seen that issue of 
Scientific American how hidden can such logic be?

-- 
********************************************************************
Paul E. Bennett...............<email://Paul_E.Bennett@topmail.co.uk>
Forth based HIDECS Consultancy
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-510979
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

On 2010-10-31, Paul E. Bennett <Paul_E.Bennett@topmail.co.uk> wrote:
> Simon Clubley wrote:
>
> [%X]
>
>> Before these and similar processors are used in products, what tests do
>> companies perform to make sure that some nasty logic surprises have not
>> been left in them ?
>
> Apart from incorrect maths functions and inverted logical operations?
>  

Yes. The focus here is on processors with additional logic designed to
remain hidden but with the ability to compromise system security at some
future point in time upon some trigger occuring.

>
> In dealing with components from suppliers I obtain certificates of 
> conformity to the data-sheet. With more complex logic devices, I run tests 
> on a few sample components to the extent of satisfying myself that the 
> devices are as described in the data-sheet. Not having seen that issue of 
> Scientific American how hidden can such logic be?
>

Very hidden and your tests as described above would be unlikely to identify
such malicious logic.

Normally I have associated such threats with things like trojan network
cards whose boot code executes during system startup. However, the Scientific
American issue was primarily concerned with the compromise of the processor
itself in that additional logic could be designed into the processor itself.
(The basic argument is that it is impossible in current processors, due to
their complexity, to test _all_ possible logic paths.)

Such a device would appear to operate normally until a trigger sequence was
executed. If this is a viable threat, then it takes the issue of hardware
based spying to a whole new level. What I don't know is if this _is_ a
viable threat or not.

The one thing I do take issue with in the article is the article's focus on
a date and time trigger as unless that functionality is built into the
processor itself, it would mean that the malicious logic would need to know
how to access that information from across the system bus.

This doesn't change the fact that such malicious logic could be triggered
in many other ways such as, for example, by a opcode sequence executed by
normal unprivileged user mode code.

Simon.

-- 
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world