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Clang now makes binaries an original Pi B+ can't run

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Re: Clang now makes binaries an original Pi B+ can't run

#61

Post by jeffparsons »

einr wrote: post #37
yjftsjthsd-h wrote: post #30

Earlier quoted context omitted.

> When the Raspberry Pi B+ was released (2014), the ARM core it used was already 11 years old (using the ARM1176 core from 2003). IIRC the original Pi used leftover chips from a TV box, which is the kind of product that IME never ships more compute than they have to, for price reasons.

TV boxes IME usually ship with less compute than they have to [in order to provide reasonable UX] ;)

And kiosks, like the McDonald's ordering kiosks. I wouldn't be surprised if they spend more on installation than on building the device itself!

Re: Clang now makes binaries an original Pi B+ can't run

#62

Post by actionfromafar »

adhesive_wombat wrote: post #58
einr wrote: post #37

Earlier quoted context omitted.

TV boxes IME usually ship with less compute than they have to [in order to provide reasonable UX] ;)

Anything to satisfy whichever law it is that says "lagginess remains constant".

"Huh, this CPU is kind of snappy running native code now. What should we do?"

"Let's move application development to Python then, I suppose."

"Thanks, that fixed it."

Probably what happened in my 55" smart TV dev team.

Re: Clang now makes binaries an original Pi B+ can't run

#63

Post by actionfromafar »

kazinator wrote: post #57
mid-kid wrote: post #54

Earlier quoted context omitted.

She was building on the B+ in the later example of the blog.

Ah I see that now. The interesting question there is why does the clang binary itself run on the old hardware? It must be that the distro build uses a different compiler configuration for itself from the configuration imbued into the installed clang. Maybe it even builds clang twice: once to produce a clang that runs on the machine that builds the distro, which then compiles the packages, including the clang to run o…

Or the build system uses GCC.

Re: Clang now makes binaries an original Pi B+ can't run

#64

Post by codedokode »

phendrenad2 wrote: post #50
RantyDave wrote: post #46

Earlier quoted context omitted.

Phones, not TV's, but that's pretty much the idea. Even better, the ARM core was tacked on as a sort of "dammit, I supposed we'll have to run applications" kinda thing and isn't even necessarily initialised during boot. Raspberry Pi's actually boot on a really fringe processor called a VideoCore. Arguably the GPU bootstraps the CPU, which makes my brain hurt.

I guess technically a CPU core within the GPU ASIC block loads code into the main CPU. What a weird design. Feels like the kinda of things that Wozniak would come up with to shave cost from the Apple Macintosh.

Could it be a protection of IP? This way program on main CPU cannot access initialization code and the user cannot learn how to do it.

Re: Clang now makes binaries an original Pi B+ can't run

#65

Post by swiftcoder »

RantyDave wrote: post #46
yjftsjthsd-h wrote: post #30

Earlier quoted context omitted.

> When the Raspberry Pi B+ was released (2014), the ARM core it used was already 11 years old (using the ARM1176 core from 2003). IIRC the original Pi used leftover chips from a TV box, which is the kind of product that IME never ships more compute than they have to, for price reasons.

Phones, not TV's, but that's pretty much the idea. Even better, the ARM core was tacked on as a sort of "dammit, I supposed we'll have to run applications" kinda thing and isn't even necessarily initialised during boot. Raspberry Pi's actually boot on a really fringe processor called a VideoCore. Arguably the GPU bootstraps the CPU, which makes my brain hurt.

This sort of thing is not uncommon in the embedded space. Lots of devices basically built on a DSP with a tiny arm core tacked on the handle application logic

Re: Clang now makes binaries an original Pi B+ can't run

#66

Post by opello »

orra wrote: post #60
opello wrote: post #59

Earlier quoted context omitted.

I really wish I understood the Debian change management process better. I guess I don't even really know if Raspbian is actually maintained by Debian. But, when comparing [1] to [2], the rules file has a nice test that says "if DEB_HOST_ARCH is armhf, set the LLVM_HOST_TRIPLE to armv6k..." which seems to confirm a build configuration change. [1] http://raspbian.raspberrypi.org/raspbian/pool/main/l/llvm-to... [2] http…

To answer your incidental question, Raspian is maintained by Raspberry Pi folks, not Debian.

Ah, thanks! I dug a little more and found that the original test [1] from llvm-toolchain was a little different in the upstream Debian repository. It set the triple to armv7l for armhf hosts.

But I haven't yet found a similar repository on the Raspbian side. I guess I'd expect to find it within their GitHub org, but my searching didn't reveal it.

[1] https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/comm...

Re: Clang now makes binaries an original Pi B+ can't run

#67

Post by b112 »

jeffparsons wrote: post #61
einr wrote: post #37

Earlier quoted context omitted.

TV boxes IME usually ship with less compute than they have to [in order to provide reasonable UX] ;)

And kiosks, like the McDonald's ordering kiosks. I wouldn't be surprised if they spend more on installation than on building the device itself!

I haven't interacted with these much, but in all such things, eg TVs, others, I get peeved at the thought process.

Typical dev time for a new UI from scratch is years. And price drop on parts and their availability will be different down the road.

I wonder of people are running all tests, DEV work in KVM or other emulation stacks for DEV, but then not accurately locking clock rate, and limiting RAM during testing.

Because I'd quit as a DEV, if I saw the fruits of my labours, turning out as complete crap and a laughing stock. I wouldn't want my name associated with laggy, crashy, frustrating junk. I'd want no part of it, no part of everyone hating my work.

And further, how the hell does laggy crap get past the CTO? CEO? I've seen lag just trying to change the channel!

I mean, outside of caring about customers every buying anything with your name again, there's the laughing stock factor.

"Hi, I'm CEO of crappy corp"

"Wow, you must be really proud of yourself, dumbass"

I just don't get it. CEO bonuses aside, saving 10 cents on a part, over 10M units is still only $1M extra profit, and the CEO might see a tiny fraction, as a bonus, of that extra profit.

I don't grok.

Re: Clang now makes binaries an original Pi B+ can't run

#68

Post by ajb »

RantyDave wrote: post #46
yjftsjthsd-h wrote: post #30

Earlier quoted context omitted.

> When the Raspberry Pi B+ was released (2014), the ARM core it used was already 11 years old (using the ARM1176 core from 2003). IIRC the original Pi used leftover chips from a TV box, which is the kind of product that IME never ships more compute than they have to, for price reasons.

Phones, not TV's, but that's pretty much the idea. Even better, the ARM core was tacked on as a sort of "dammit, I supposed we'll have to run applications" kinda thing and isn't even necessarily initialised during boot. Raspberry Pi's actually boot on a really fringe processor called a VideoCore. Arguably the GPU bootstraps the CPU, which makes my brain hurt.

Are you sure about that? As I understand it, the other product that chip was used in was a Roku stick.

It's true that videocore was intended to be a GPU for phones, though.

Re: Clang now makes binaries an original Pi B+ can't run

#69

Post by JonChesterfield »

I doubt this is a deliberate change. Picking up information from the environment - a sibling mentions /etc/env.d/gcc - seems fairly likely. I'd guess the default triple is something like arm-unknown-linux unless clang finds or is is told something more specific to use, and the mechanism by which it gets told to use something more specific has fallen over.

This might mean there are no arm v6 buildbots running, or it might mean there are ones running but the implicit configuration is still working on them.

LLVM is a really good cross compiler. Build for any target from any target, no trouble. Clang is less compelling - if it's built with the target, and you manage to tell it what target to build for, it'll probably do the right thing (as in this post - it guessed wrong, but given more information, did the right thing). Then the runtime library story is worse again - you've built for armv4 or whatever, but now you need to find a libc etc for it, and you might need to tell the compiler where those libraries and headers are, and for that part I'm still unclear on the details.

Re: Clang now makes binaries an original Pi B+ can't run

#70

Post by orra »

opello wrote: post #66
orra wrote: post #60

Earlier quoted context omitted.

To answer your incidental question, Raspian is maintained by Raspberry Pi folks, not Debian.

Ah, thanks! I dug a little more and found that the original test [1] from llvm-toolchain was a little different in the upstream Debian repository. It set the triple to armv7l for armhf hosts. But I haven't yet found a similar repository on the Raspbian side. I guess I'd expect to find it within their GitHub org, but my searching didn't reveal it. [1] https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/comm...

Yeah, Raspbian doesn't seem to be developed as a community project. There's no package tracker[1] like Debian or Ubuntu. I suppose they don't tend to diverge much, in practice.

Anyway, I suppose this all means Raspberry Pi OS/Raspbian are able to patch this, without requiring it to first be fixed in Debian or Clang.

[1] https://raspberrypi.stackexchange.com/questions/1179/does-ra...

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