
ARM's Cortex A57 and Cortex A53: The First 64-bit ARMv8 CPU Cores - sciwiz
http://www.anandtech.com/show/6420/arms-cortex-a57-and-cortex-a53-the-first-64bit-armv8-cpu-cores
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haberman
Looks very cool; the idea of having "big" and "little" processors on the same
SoC is interesting. I wondering if this is a big win vs. just having a "big"
processor that is frequently put into idle mode when not needed.

As a side note, does anyone else find the ARM naming conventions totally
impossible to follow? I look at the list of ARM models
([http://en.wikipedia.org/wiki/List_of_ARM_microprocessor_core...](http://en.wikipedia.org/wiki/List_of_ARM_microprocessor_cores))
and have no idea where to begin. The family/architecture/core scheme means you
can have a single chip that is an ARM11 family, ARMv6 architecture,
ARM1136JF-S core. How do people make sense of this?

As someone who's writing a library that I want to be supported across all (or
most) ARM cores, I don't have any idea how many different chips I'd need to
test against to get a representative sample. There are so many optional
features (NEON, Thumb, Thumb-2, VFP, etc) that seems to be supported in
various combinations across the different models. It's like a maze and I never
have any idea how a new model I read about fits in.

~~~
Nursie
Does your library have to be a single compiled binary across all these
variants? If so, good luck...

Otherwise, hopefully, a compiler takes care of most of the mess for you and
gets you the best it can on the platform you're targeting. You might need to
check that things would run on a variety of configurations - for instance
hardfloat and softfloat do indeed have very different performance profiles
when it comes to floats. Thumb shouldn't bother you too much as an application
programmer (unless I'm very much mistaken) because it's just another
instruction set for a compiler to target.

Errr....

You can get into all sorts of complications when actually looking at the
platform ABIs. Debian, for instance, seem to have something of a lowest-
common-denominator approach that targets features present everywhere. Which is
then why someone had to rebuild it to get decent FP performance out of the
Raspberry Pi which had hard-float...

Part of the complexity is that ARM is a licensed architecture. Some companies
license the design of the whole core, some incorporate their own stuff and
some just license the instruction set and do their own stuff otherwise.

What do you mean 'supported across all (or most) ARM cores'? Because that's
huge and varies massively. There are the sub-100MHz embedded devices I happen
to be working on at the moment (which may be running any of a load of
different OSs), there are ARM cores embedded in all sorts of controllers where
I wouldn't think you'd want to run, then there's the multi-core multi-GHz
stuff from the likes of Samsung, Qualcomm and Marvell...

~~~
sciurus
" Debian, for instance, seem to have something of a lowest-common-denominator
approach that targets features present everywhere."

Debian actually has three ARM ports in progress.

ArmEabiPort - newer port using the "new" ABI (EABI), supported on ARM v4t and
higher. First released with 5.0 (Lenny). GNU Triplet: arm-linux-gnueabi

ArmHardFloatPort - the latest 32-bit port, using the hard-float version of the
"new" ABI (EABI), targetting ARM v7 and up. To be released with 7.0 (Wheezy).
GNU Triplet: arm-linux-gnueabihf

Arm64Port - the latest port, for the 64-bit ARMv8 architecture. Likely to be
released with 8.0 (Jessie). GNU Triplet: aarch64-linux-gnu

<http://wiki.debian.org/ArmPorts>

~~~
Nursie
Perhaps it would have been more accurate to say that's the way debian used to
do it then, I know there's been a lot of movement on hardfloat support.

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ChuckMcM
Pretty creative stuff. I am looking forward to AMD building an eco-system
around these things. My guess is that if AMD could deliver 64 bit ARM server
chips and full programming documentation to support a robust Linux server OS
architecture they could take a huge chunk of server share away from Intel
based machines.

My reasoning is that people started migrating to AMD when they had a 64 bit
x86 architecture and Intel didn't. That showed me that folks were willing to
go with AMD if they provided something that Intel wouldn't (or couldn't).
Given that ARM isn't bogged down by Intel's staggering licensing challenges
(chipsets, busses, instruction sets, etc) this suggests a very interesting
couple of years ahead.

~~~
wmf
It's not clear how AMD's ARM chips will be any better than the other ones
(e.g. Calxeda), though.

~~~
ChuckMcM
Well they could start by replacing Calexda's 32 bit physical memory addressing
(4GB) with 40 bit physical addressing (1TB) all my servers have 96GB and will
have 192GB on the next iteration. I'd love to put 512GB of 'flash' memory in
the physical address space And then bump of L2 Cache to 12MB maybe 16MB.

~~~
wmf
To be clear, let's compare an AMD chip based on the Cortex-A57 against a
Calxeda chip based on the Cortex-A57, or maybe a Samsung chip based on the
Cortex-A57. The GPU is an obvious differentiator, but not in servers.

~~~
ChuckMcM
Sure, but one of the challenges for 'SoC' companies vs 'server' chip companies
has been that 'SoC' companies continue to think that the 'system' is mostly
just their 'chip' (hence the SoC moniker rather than say CPU moniker)

To date, I am not familiar with any ARM licensees who have made 'CPUs' vs
'SoC's, they may be out there but I've not seen them yet. Something where the
ARM CPU is the core but the system designer can pick the level of IO or memory
that is included. Basically a socketed ARM chip like server CPUs are socketed
today.

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mtgx
It sounds like A53 will start at 1.3 Ghz, and A57 will end at 3 Ghz. A 3 Ghz
ARM CPU. Interesting:

"For those who are still looking for gigahertz performance numbers Hurley
sais]d that new A-50 family will deliver performance ranging from 1.3
gigahertz to 3 Gigahertz depending on how the ARM licensees tweak their
designs."

[http://gigaom.com/2012/10/30/meet-arms-two-newest-cores-
for-...](http://gigaom.com/2012/10/30/meet-arms-two-newest-cores-for-faster-
phones-and-greener-servers/)

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hemancuso
Any Intel employees in the crowd? What's the level of worry surrounding ARM
these days?

Given Intel's high levels of competitive paranoia, news like this must have
people fairly worried. Not to mention the explosive growth in adoption of the
ISA over the past few years.

~~~
czhiddy
I spoke to my friend @ Intel a while back, and he said that the company viewed
Samsung as their main rival (not AMD, not ARM). His argument was that Intel's
main competitive advantage (and where the majority of spending/R&D happens)
was their fabs, and Samsung was the only other company that could come close
to competing on that front.

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Jonanin
I wish they would release the architecture reference manual to the public...
all we have is the instruction set right now. Not enough to do bare metal/os
work.

~~~
robot
you can get it if you register at arm.com and agree to their legal terms.

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codex
I don't believe these will be the first 64-bit ARMv8 CPU cores. Doesn't that
honor go to Applied Micro's X-Gene SOCs? They'll ship a lot sooner than 2014.

