ARMv9 Architecture Helps Lift Arm to New Financial Heights

China will likely be the country taking forward RISC-V and ditching Arm and x86 completely. With USA trying to stop other countries from using latest Chinese tech they are given more reason to ditch any and all propitiatory US tech. So over the next decade I expect RISC-V architecture to enter and flood all Chinese tech devices from Tvs to cars and everything else that needs a CPU.

I personally hope China get's competitive in the node size as well as I want gpu and cpus start getting cheaper every generation again as once TSMC got big lead over Intel/Samsung and Nvidia got a big lead over AMD prices have stopped coming down generation to generation for CPU's and GPU's

There are an incredible number of companies designing their own RISC-V cores right now. Some of them are even are making some of their designs entirely open source so that they are royalty free. The highest end designs are not, but it is hard to imagine their creators not undercutting ARM’s license fees since that is money that they would not have otherwise.

As for Qualcomm, they won the lawsuit ARM filed against them. Changing from ARM to RISC-V would delay their ambition to take marketshare from Intel and AMD, so they are likely content to continue paying ARM royalties because they have their eyes on a much bigger prize. It also came out during the lawsuit that Qualcomm considers their in-house design team to be saving them billions of dollars in ARM royalty fees, since they only need to pay royalties for the ISA and nothing else when they use their own in-house designs.

Correct me if I am wrong, but in RISC-V's case, you would be licensing the core design alone, not a license for the ISA plus the core on top.

Right now, AFAIK only Apple is serious about designing their own ARM cores, while there are multiple competing implementations for RISC-V (which are still way behind both ARM and x86, but slooowly making their way).

VERY long-term, I expect RISC-V to become more competitive, unless whoever-owns-ARM-at-the-time adjusts strategy.

Either way, I'm glad to see competition after decades of Intel/x86 dominance.

Yes, but the playing field is different. Anyone can become a Risc-V IP provider and many such companies have already been created.

So far, Qualcomm is not paying the royalty rate hikes since they are selling ARM hardware using cores covered under the ARMv8 architectural license that they obtained before SoftBank started pushing ARM to improve profitability.

It is interesting that you should mention MediaTek. They joined the RISC-V Software Ecosystem in May 2023:

https://riseproject.dev/

It seems reasonable to think that they are considering jumping ship. If they are designing their own in-house CPU cores, it will likely be a while before we see them as part of a mediatek SoC.

In any case, people do not like added fees. They had previously tolerated ARM’s fees since they were low, but now that they are raising them, people are interested in alternatives. At least some of ARM’s partners are paying the higher for now, but it is an incentive to move to RISC-V, which is no fee for the ISA and either no fee or low fee for IP cores. For example, the hazard3 cores that the Raspberry Pi Foundation adopted in the RP2350 did not require them to pay royalty fees to anyone.

Huawei is probably the one that possibly might move away from arm because they have their own operating system. The US could tighten their controls more and ban them from arm altogether- so far they are prohibited from arm 9.

I am not sure Huawei would go for riscv - they could easily go for their own isa or an arm fork.

Switching microcontrollers means you have a lot of work to do to redo the HW design, re-run all of your pre-production testing, update mfg/QA with new processes and tests, possibly rewrite some of your application.. and you need to price in a new part to your BOM, figure out a secure supply for some number of years... And that just assumes you don't want to do even more work to take advantage of the new chip's capabilities by rewriting even more of your code. All while your original CPU probably still does fine because this is embedded we're talking about and your product already does what it needs to do.

RISC-V is even worse: The Cortex-M series have standardized interrupt handling and are built so you can avoid writing any assembly for the startup code.

Meanwhile the RISC-V spec only defines very basic interrupt functionality, with most MCU vendors adding different external interrupt controllers or changing their cores to more closely follow the faster Cortex-M style, where the core itself handles stashing/unstashing registers, exit of interrupt handler on ret, vectoring for external interrupts, ... .

The low knowledge/priority of embedded of RISC-V can be seen in how long it took to specify an extension tha only includes multiplication, not division.

Especially for smaller MCUs the debug situation is unfortunate: In ARM-World you can use any CMSIS-DAP debug probe to debug different MCUs over SWD. RISC-V MCUs either have JTAG or a custom pin-reduced variant (as 4 pins for debugging is quite a lot) which is usually only supported by very few debug probes.

RISC-V just standardizes a whole lot less (and not sensibly for small embedded) than ARM.

The RP2040 and RP2350 are fairly big changes from the status quo, although they are not very energy efficient compared to other MCUs. Coincidentally, the RP2350 is part of the RISC-V ecosystem. It has both RISC-V and ARM cores and lets you pick which to use.

> It's because the software ecosystem around them is so incredibly lousy and painful.

This is reaching breaking point entirely because of how powerful modern MCUs are too. You simply cannot develop and maintain software of scale and complexity to exploit those machines using the mainstream practices of the embedded industry.

There are no similarities between Cortex-M7 and Cortex-A7 from the POV of obsolescence.

Cortex-M7 belongs to the biggest-size class of ARM-based microcontrollers. There is one newer replacement for it, Cortex-M85, but for now Cortex-M7 is not completely obsolete, because it is available in various configurations from much more vendors and at lower prices than Cortex-M85.

Cortex-M7 and its successor Cortex-M85 have similar die sizes and instructions-per-clock performance with the Cortex-R8x and Cortex-A5xx cores (Cortex-M5x, Cortex-R5x and Cortex-A3x are smaller and slower cores), but while the Cortex-M8x and Cortex-R8x cores have short instruction pipelines, suitable for maximum clock frequencies around 1 GHz, the Cortex-A5xx cores have longer instruction pipelines, suitable for maximum clock frequencies around 2 GHz (allowing greater throughput, but also greater worst-case latency).

Unlike Cortex-M7, Cortex-A7 is really completely obsolete. It has been succeeded by Cortex-A53, then by Cortex-A55, then by Cortex-A510, then by Cortex-A520.

For now, Cortex-A55 is the most frequently used among this class of cores and both Cortex-A7 and Cortex-A53 are truly completely obsolete.

Even Cortex-A55 should have been obsolete by now, but the inertia in embedded computers is great, so it will remain for some time the choice for cheap embedded computers where the price of the complete computer must be well under $50 (above that price Cortex-A7x or Intel Atom cores become preferable).

The way you put it makes it sound like STM have a serious security problem with their manufacturing.

Some chips that have come out in the past 3 years with Cortex A7:

Microchip SAMA7D65 and SAMA7G54. Allwinner V853 and T113-S3.

It's not like a massive stream of A7's. But even pretty big players don't really seem to have any competitive options to try. The A-35 has some adoption. There is an A34 and A32 that I don't see much of, don't know what they'd bring above the A7. All over a decade old now and barely seen.

To be fair, just this year ARM announced Cortex-A320 which I don't know much about, but might perhaps be a viable new low power chip.

even some new SOC from Rockchip use DDR2 RAM

Apple is ignoring desktop?

M4 has ">2x better performance per watt" than either Intel or AMD only in single-threaded applications or applications with only a small number of active threads, where the advantage of M4 is that it can reach the same or a higher speed at a lower clock frequency (i.e. the Apple cores have a higher IPC).

For multithreaded applications, where all available threads are active, the advantage in performance per watt of Apple becomes much lower than "2x" and actually much lower than 1.5x, because it is determined mostly by the superior CMOS manufacturing process used by Apple and the influence of the CPU microarchitecture is small.

While the big Apple cores have a much better IPC than the competition, i.e. they do more work per clock cycle so they can use lower clock frequencies, therefore lower supply voltages, when at most a few cores are active, the performance per die area of such big cores is modest. For a complete chip, the die area is limited, so the best multithreaded performance is obtained with cores that have maximum performance per area, so that more cores can be crammed in a given die area. The cores with maximum performance per area are cores with intermediate IPC, neither too low, nor too high, like ARM Cortex-X4, Intel Skymont or AMD Zen 5 compact. The latter core from AMD has a higher IPC, which would have led to a lower performance per area, but that is compensated by its wider vector execution units. Bigger cores like ARM Cortex-X925 and Intel Lion Cove have very poor performance per area.