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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
#92[flagged]
It's not explicitly stated but in her reproduction she is actually running it on the pi, and compilers very much do normally compile for the arch that they are running on by default. A compiler which compiles for a different arch is called a cross-compiler. Unless you explicitly asked for a cross compile, it is indeed surprising for a compiler to emit a binary that won't run on the same machine.
> It's not explicitly stated but in her reproduction she is actually running it on the pi
This is what the post says:
>> This used to work in the old version (bullseye). It now breaks in the current one (bookworm). I figured, okay, maybe it's doing some optimization because it was built on the 4B. So, I went and did a build on the B+ natively. It also broke.
If that's not an explicit statement that she's compiling on the target platform, what is?
Re: Clang now makes binaries an original Pi B+ can't run
#93I 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 m…
Most distros and compilers effectively dropped ARMv6 a couple of years back - I had similar trouble building binaries for my old Synology NAS.
Alpine Linux might still support it I think.
Re: Clang now makes binaries an original Pi B+ can't run
#94Earlier 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.
Ehhh, video core is basically just a (iirc multi-core/-thread) vector processor.
Funnily enough, this also makes these rather cheap number crunching hard real time chips with the high-bandwidth IO (for hard-real-time) of a Pi. Notably, it's camera/display interfaces.
Re: Clang now makes binaries an original Pi B+ can't run
#95Earlier quoted context omitted.
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.
Doesn't really help when the VC firmware is loaded from the SD card anyways
Re: Clang now makes binaries an original Pi B+ can't run
#96Earlier quoted context omitted.
Most developers suck.
Even if it were true that is not the problem. Even sucky devs can crank out code that runs reasonably fast. It just depends on whether the company sees it as a required feature.
Making your code run quickly will not help if your software architecture is inefficient or optimized against the customer as so many web applications are these days, for example. There are many commercial web pages that appear and approximately ten seconds later clicking on a button will actually do something. I am not sure why that it considered acceptable, but customer experience doesn't seem to rank very high on the list of priorities.
Re: Clang now makes binaries an original Pi B+ can't run
#97I 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 m…
> Picking up information from the environment - a sibling mentions /etc/env.d/gcc - seems fairly likely. Why would CLANG do this ?
Clang already replicates a bunch of flags, macros, and behaviors from gcc. The objective is to be a drop-in replacement, and make the developer experience much nicer when migrating. There are some rough corners, of course, but overall it’s actually very nice.
Re: Clang now makes binaries an original Pi B+ can't run
#98Earlier 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.
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
> Lots of devices basically built on a DSP
There were many X terminals running off nothing but a Texas 34010, which was a very DSP-like CPU that ended up in a lot of high-end graphics acceleration boards for PCs and Macs (and Unix workstations).
The fact it could boot up an X server is quite extraordinary.
I wonder what the VideoCore looks like to the programmer.
Re: Clang now makes binaries an original Pi B+ can't run
#99Earlier 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.
I suspect it's less about having CPU as afterthought, than about how and who is to take CPU out of "awaiting to be booted" state. Ancient CPU simply had a BIOS mask ROM hardwired to reset vector and immediately load from it upon release of reset line, nowadays and on more complex systems, I believe that's what Intel Management Engine/Apple Secure Enclave/VideoCore GPU/etc. will do, not the main CPU itself.
Re: Clang now makes binaries an original Pi B+ can't run
#100Earlier 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.
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.
I am only going off my memory, so I could be mistaken. But IIRC the OG pi used processors originally designed for phones (at least the one that hit the market, eraly prototypes were based on Atmel micros), The iPhone used a processor originally designed for a set-top box from Samsung which was then underclocked to save on battery.
IIRC they realised that the micros were not going to cut it, they went to Broadcom (Which Eben was working for at the time) and they were able to supply some "overstock processors" for cheap, which became the processor used in the Pi. Remember at the time the Pi was never designed to be for "makers" but to be a cheap computer to help better kickstart education, it was never designed for "us", but we all said "hey, cheap little linux computer, I'll take 5!