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So you want to build an embedded Linux system? (2020)

jaycarlson.net

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Re: So you want to build an embedded Linux system? (2020)

#31

Earlier quoted context omitted.

Duckduckgo, "NXP LPC", sidebar, quote from wikipedia: > LPC is a family of 32-bit microcontroller integrated circuits by NXP Semiconductors. Not a microprocessor. You are the second guy to pull this on me. Do people even read what i write? Did i write unclearly?

Perhaps you're just outdated. Nobody ships a core alone on a chip anymore. That died with the 68000 or ARM7TDMI.

x86 is a classic microprocessor architecture. I'm confident it is not outdated yet, as im using a fairly modern x86 desktop right now at the moment. RAM and chipset are separate from the processor.

Re: So you want to build an embedded Linux system? (2020)

#32

Earlier quoted context omitted.

It's a pointless distinction by and large. Microcontrollers may or may not have storage for firmware. Requiring an off-chip flash is nothing new. Microcontrollers have SRAM, but so do processors. That's where the firmware runs before it gets the DRAM running. Microcontrollers may include a bunch of peripherals, but so do processors. Especially so if you refer to SoCs as processors, like the article here does. And SoC…

The distinction used to be "Whether the bus is exposed externally". > Microcontrollers have SRAM, but so do processors. That's where the firmware runs before it gets the DRAM running. Which microprocessor architecture does this?

Just about any with cache will let you pin last level cache to assist boot up.

I've done this with PowerPC cores that no one would call microcontrollers.

Re: So you want to build an embedded Linux system? (2020)

#33

Earlier quoted context omitted.

Perhaps you're just outdated. Nobody ships a core alone on a chip anymore. That died with the 68000 or ARM7TDMI.

x86 is a classic microprocessor architecture. I'm confident it is not outdated yet, as im using a fairly modern x86 desktop right now at the moment. RAM and chipset are separate from the processor.

Then maybe the hackers using x86 boards in their 'embedded Linux systems' can chime in.

Re: So you want to build an embedded Linux system? (2020)

#34
post #25

Earlier quoted context omitted.

Wine is not an emulator, it's a PE loader and a Win32 API for Unix. And XTerm is more like a terminal simulator .

Wine actually IS an emulator, just not the kind of emulator you think of. While wine is not an virtual machine, it literally emulates the win32 api. https://web.archive.org/web/20150928042254/http://wiki.wineh... I mentioned the shift of meaning to "virtual machine" in the post you replied to, please read it more carefully. Emulation and Simulation are different in some regard: emulation is only imitating some aspect…

I'd argue that wine is a bit of a stretch considering that we're on the third implemention of win32 in Microsoft land as well (DOS/win32s, Win95, NT/Win32k). At that point win32 is a concept already abstracted away from a specific implementation

I totally agree with your main point though that emulation is a broader topic than is generally thought.

Re: So you want to build an embedded Linux system? (2020)

#35

Earlier quoted context omitted.

x86 is a classic microprocessor architecture. I'm confident it is not outdated yet, as im using a fairly modern x86 desktop right now at the moment. RAM and chipset are separate from the processor.

Then maybe the hackers using x86 boards in their 'embedded Linux systems' can chime in.

Perfect, as i own a RDC 3210 board. Here is someone else with the same board + pictures: https://forum.archive.openwrt.org/viewtopic.php?id=19168

It has a x86 Microprocessor architecture, but it is not IBM PC compatible because it does not has an BIOS, instead using a more embedded-style RedBoot setup.

Maybe you should do a quick web search before talking shit.

Re: So you want to build an embedded Linux system? (2020)

#36

Earlier quoted context omitted.

Perhaps you're just outdated. Nobody ships a core alone on a chip anymore. That died with the 68000 or ARM7TDMI.

x86 is a classic microprocessor architecture. I'm confident it is not outdated yet, as im using a fairly modern x86 desktop right now at the moment. RAM and chipset are separate from the processor.

> x86 desktop right now at the moment. RAM and chipset

"chipset" is very different than a traditional microprocessor chipset though on that. E.g. you don't have an exposed system bus outside the CPU, but rather specialized interfaces. (And ARM systems have evolved the same way over their history)

Re: So you want to build an embedded Linux system? (2020)

#37
post #36

Earlier quoted context omitted.

x86 is a classic microprocessor architecture. I'm confident it is not outdated yet, as im using a fairly modern x86 desktop right now at the moment. RAM and chipset are separate from the processor.

> x86 desktop right now at the moment. RAM and chipset "chipset" is very different than a traditional microprocessor chipset though on that. E.g. you don't have an exposed system bus outside the CPU, but rather specialized interfaces. (And ARM systems have evolved the same way over their history)

What about the slots i plug my RAM sticks into? Do they not count because it goes over the north bridge?

Re: So you want to build an embedded Linux system? (2020)

#38
post #5

I'm curious how the landscape has changed with the chip shortages since this was written. My all time favorite SoM was the CHIP Pro, but sadly at $7 (or was it $13?) it was indeed too good to be true and the company went out of business.

I have a pile of them in my drawer, as many as I could get my hands on (maybe 8 or 12?)

They're great. In my head they were "something that had the stuff that annoyed me about RaspberryPis fixed".

I should dig some out and see if there's a way to update the OS to something recent-ish.

I think I've still got a cluster of 4 of them, 3 running RTL SDR and one analysing the signals and pulling interesting data out. (Last data file I have here from that is Dec 2018...)

Re: So you want to build an embedded Linux system? (2020)

#39

Earlier quoted context omitted.

1) This is a distinction without a difference. 2) SRAM is almost always on the die , not external. Here's a die shot of a random STM32 (cortex M): [1]. The SRAM is quite obvious. [1] https://s.zeptobars.com/GD32F103CBT6-Si-HD.jpg

It is a meaningful distinction. A microprocessor architecture would require support chips, like a south- and north bridge, plus RAM in additional chips. x86 being the classic example. Here [1] is an example of a microprocessor board, you can see the MX support chips on both sides of the CPU. As you can see, the RAM (and the most of the address space-mapped things) is not on-chip. The bus is wired across the PCB. [1]…

Even x86 has on-die SRAM that can be used in boot. It's better known as L1, L2, and L3, but you can configure Intel's FSP to make it usable for boot code with the so-called cache-as-RAM feature. The technical details are different than e.g. ARM because it's cache rather than properly addressable memory, but the general idea is the same.

All the RAM you see on the motherboard is DRAM. It's a totally separate thing and happens to be what the FSP initializes after it loads stuff into SRAM.

Re: So you want to build an embedded Linux system? (2020)

#40
post #36

Earlier quoted context omitted.

> x86 desktop right now at the moment. RAM and chipset "chipset" is very different than a traditional microprocessor chipset though on that. E.g. you don't have an exposed system bus outside the CPU, but rather specialized interfaces. (And ARM systems have evolved the same way over their history)

What about the slots i plug my RAM sticks into? Do they not count because it goes over the north bridge?

Modern x86 CPUs integrate the DRAM controller directly (e.g. with Intel ever since Nehalem, ~2008) and not over a bus through the northbridge. From that point on I wouldn't count it if you insist on a strict definition, no - it's roughly the same as if you put a socket between a current higher-end ARM chip with external memory and the connected DRAM chips. Chipset is relegated to dealing with I/O to peripherals mostly - and nowadays the CPUs also provide PCIe lanes directly, with the chipset often adding a few more, often slower ones.

Traditional microprocessors are getting really rare, even though pretty much all the modern architectures started as them, and thus some use the term more widely. Some vendors use the differentiation between microcontrollers and application processors now, which also isn't a 100% clear line and explicit crossover models existing, but more useful today and avoids the fights over "what's a microprocessor today". (where "application processor" ~ "can reasonably run a full OS like Linux"). But that's also often limited to discussion in embedded use cases again, e.g. I don't know if they'd call a standard desktop CPU that or insist on some arbitrary level of "embeddedness"... Not that standard desktop CPUs don't end up embedded, but that's another discussion entirely.

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