
ARM adopts 64-bit architecture  - codedivine
http://www.tgdaily.com/hardware-features/59302-arm-adopts-64-bit-architecture
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Symmetry
This link has a bit more information. [http://www.arm.com/about/newsroom/arm-
discloses-technical-de...](http://www.arm.com/about/newsroom/arm-discloses-
technical-details-of-the-next-version-of-the-arm-architecture.php)

I wonder how these two new modes will relate to existing modes like Thumb2?

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brigade
Even more information:
<http://www.arm.com/files/downloads/ARMv8_Architecture.pdf>

The answer is that there is only one 64-bit ISA, but all current 32-bit modes
are still supported.

~~~
Symmetry
Yeah, I just found that this morning. I'm sort of leery of the move to 32
GPRs.

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pkaler
ARM is basically doing to Intel what Clayton Christensen taught Andy Grove to
do with the Celeron.

<http://hbr.org/2010/07/how-will-you-measure-your-life/ar/1>

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watmough
That's a great story. Thanks for posting it.

Actionable material.

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ricw
My prediction: once this architecture is in the release channels, Intel is out
of them. In a matter of years, Intel will be the dinosaur of microprocessors.
Unless Intel also (re-)embraces ARM. Its simply a matter of price and
configurability. ARM is simply unbeatable when it comes to price. Let alone
energy efficiency. Its time to short Intel shares..

~~~
luu
ARM is unbeatable in terms of price right now, but that's because they have
much smaller parts that are much cheaper to produce. What makes you think that
will still be true if they want to approach the performance of mainstream
Intel parts?

Historically, low-end parts have managed to kill high-end parts by selling in
larger volumes and amortizing their fixed costs over a larger base. ARM sells
in huge volumes, but how is selling $1 embedded chips going to help them
amortize the cost of their high end stuff? Decades ago, doing that sort of
thing would helped Intel fill up their idle fab time while competitors like
DEC struggled to pay for their fabs, but ARM has never owned its own fabs, and
selling completely different low-end parts doesn't really help amortize the
cost of masks, post-silicon debug, etc. of their high end parts.

I'm also skeptical that ARM will retain its power:performance advantage if it
tries to scale up performance to match low-end mainstream Intel parts (e.g.,
core i3). The main reason ARM has better performance:power is that there are
diminishing returns to performance. Another is that Atom is a new product
line, and Intel doesn't have much experience trying to optimize for low-end
parts. That won't be true going forward. Yet another transient advantage ARM
has is that Intel uses a high performance process, but they've said that
they're going to have both a high performance and a power optimized process in
the future. If anything, Intel's process wizardry should give them an
advantage there, once they decide to push it. What other inherent advantages
does ARM have over x86? It's a PITA to decode x86 instructions, but the ARM
instruction set isn't very nice, either (e.g., look at how they ran out of
opcode space, and overlayed some of their "new" NEON instructions on top of
existing instructions by using unused condition codes for existing opcodes).

I wouldn't bet against ARM but, if they win, it will be because of the usual
reasons: better marketing, better business practices, and better engineering,
not because there's some inherent advantage that lets them be cheaper than
Intel. And, by the way, the configurability advantage you mention actually
hurts them in terms of cost, by increasing the fixed cost per part.

~~~
joshu
(IIRC Atom is an x86 translation layer on top of an ARM core. Am I mistaken?)

~~~
listic
Z5xx series Atoms (
[http://en.wikipedia.org/wiki/List_of_Intel_Atom_microprocess...](http://en.wikipedia.org/wiki/List_of_Intel_Atom_microprocessors#MID_processors_.28UMPC.29)
) had PowerVR GPUs (they call it GMA 500, but they have nothing in common with
Intel's own GMA's!), the ones that are normally used with ARM CPUs. Sony Made
ultra-portable Vaio P-Series with them (
<http://en.wikipedia.org/wiki/Sony_VAIO_P_series> )

Unfortunately, it looks like it all was a fluke. I haven't heard of any
notebooks with Atom Z6xx series, presumably because Windows won't run on them
because they don't have a PCI bus. With the architecture consisting of a
single model (Vaio P-Series) the possibility of running Linux is vanishing:
there was a special build[sic!] of Ubuntu that should run on it, but that's
it.

~~~
yuhong
The Oak Trail platform fixes this by using a different chipset that is PC
compatible and thus can run Windows.

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renownedmedia
Hopefully the next iteration of the Raspberry Pi will have this!

~~~
brigade
It's currently using a 6+ year old ARM11.

~~~
renownedmedia
Damn... I had no idea. I guess that would explain why my year old cell phone
is more powerful. Thanks for the info!

Perhaps Version 4 of the Raspberry Pi will use it!

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nknight
Is there any backstory on why this is only happening now? The address space
situation is already borderline in some areas of ARM usage, and cell phones
are about to break 1GB of physical RAM (if some haven't already?).

Seems like this is a couple years overdue to have anything close to a
comfortable margin.

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mbell
The instruction architecture is irrelevant to the issue of address space.

The Cortex A15 can already address up to 1TB of memory.

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masklinn
Oh? How does it handle this? Something similar to PAE? To PSE? Explicitly
using cooperative coprocessors? A completely different scheme?

Also, isn't it relevant to process-addressable (virtual) memory? Barring
explicit APIs such as AWE. As far as I know, ARM registers are 32b so a
process should not be able to load data from an address higher than the 4GB
mark (in its virtual memory), am I wrong?

~~~
mbell
Two separate issues, memory per process (which is limited to 32bits of address
space) and total physical address space available to the MMU. It is similar to
PAE in fact ARM calls it LPAE.

