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by jahboater
Sun Oct 25, 2020 9:33 am
Forum: Java
Topic: java is not supported any more on Pi0 with OS buster
Replies: 13
Views: 12213

Re: java is not supported any more on Pi0 with OS buster

In short I don't want to use a proprietary programming language and have the worry of such legal threats from such a vicious predatory company hanging over my head. I don't think it's wise for anyone to do so. +1, or even just the threat of the language being abandoned because its no longer profita...
by jahboater
Fri Oct 23, 2020 10:09 am
Forum: General discussion
Topic: Raspberry Pi 4 Overclock 2.0Ghz and Wi-Fi problem?
Replies: 6
Views: 257

Re: Raspberry Pi 4 Overclock 2.0Ghz and Wi-Fi problem?

It could also throttle or have other problems because of a low supply voltage.
If you run this command and it returns anything other than 0x0 then something is not right:

Code: Select all

vcgencmd get_throttled
by jahboater
Thu Oct 22, 2020 5:52 pm
Forum: General discussion
Topic: Programs to Run
Replies: 10
Views: 352

Re: Programs to Run

Hmm..."must get". Well for me that is: C/C++, already installed out of the box. Because Raspberry Pi OS is quite a rich development environment, and my favorite programming languages are already included, it is usable almost immediately. I do however upgrade the languages to the latest versions. Fo...
by jahboater
Thu Oct 22, 2020 5:20 pm
Forum: Other projects
Topic: How to take out the CPU completely?
Replies: 14
Views: 364

Re: How to take out the CPU completely?

PiGraham wrote:
Thu Oct 22, 2020 4:56 pm
scanning electron microscope to see any detail on the chip.
There are four CPU's, so if you break one, there are some spares.
:)
by jahboater
Thu Oct 22, 2020 5:15 pm
Forum: Bare metal, Assembly language
Topic: Acquiring an assembler
Replies: 2
Views: 186

Re: Acquiring an assembler

You will also need the linker, called "ld". Note there are two different versions of the OS for the Pi4, 32-bits and 64-bits with their own instruction sets. Your assembler programs will need to be different of course. The assembly languages are called A32 for ARM 32-bit, and A64 for Aarch64 64-bit....
by jahboater
Thu Oct 22, 2020 5:00 pm
Forum: General discussion
Topic: Overclocking rpi4 to its limits
Replies: 21
Views: 1130

Re: Overclocking rpi4 to its limits

I'm risk averse after some bad experience of losing data, plus it reduces the number of computer shaped holes in my glass windows :o :lol: After stress testing it, I also back off the frequency a bit. I tested my Pi4 at 2.1GHz and I am "reasonably" happy that its stable. But as you say, it cannot b...
by jahboater
Thu Oct 22, 2020 1:07 pm
Forum: General discussion
Topic: Programs to Run
Replies: 10
Views: 352

Re: Programs to Run

I want to use my pi as a programming computer. That's great! The Raspberry Pi OS comes pre-installed with several programming languages and a plethora of development tools to go with them. Many other programming languages are a simple "apt install" away. You have a powerful debugger (gdb), make, va...
by jahboater
Thu Oct 22, 2020 11:32 am
Forum: C/C++
Topic: RPi c++ IDE?
Replies: 10
Views: 444

Re: RPi c++ IDE?

emacs
by jahboater
Thu Oct 22, 2020 11:30 am
Forum: Beginners
Topic: New faster microsd or ssd?
Replies: 4
Views: 172

Re: New faster microsd or ssd?

The Sandisk A1 class cards are popular. The A1 class is important because they are optimized for fast random I/O (helpful for apps and OS's) instead of streaming video. In my experience the Linux (Raspberry Pi OS) disk cache is so effective that it masks differences in raw SD card speeds for day to ...
by jahboater
Wed Oct 21, 2020 9:42 pm
Forum: General discussion
Topic: Overclocking rpi4 to its limits
Replies: 21
Views: 1130

Re: Overclocking rpi4 to its limits

pidd wrote:
Wed Oct 21, 2020 8:24 pm
While its easy to prove its unstable, how do you prove its stable?
Good question.
I just stress test to a level way beyond any normal workload - preferably including something like Linpack that checks its results.
Then I know there is a safety margin.
by jahboater
Wed Oct 21, 2020 8:27 pm
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

Until, finally, someone posted a version that was short, clear and fast. In fact it could be marginally faster than the C version. Basically the same algorithm but it hit the sweet spot where the compiler could vectorize the whole thing. Not only that but with a tiny 4 character addition to the sou...
by jahboater
Wed Oct 21, 2020 6:02 pm
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

It's amazing what a big effect seemingly small, innocuous, changes can make. I think this part of the reason Godbolt is so popular, people can conveniently tweak their code around and immediately see what instructions come out. Yes. I only do tweaks if there is a reason behind it, not at random to ...
by jahboater
Wed Oct 21, 2020 10:31 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

Especially that crypto. We wrote it with Intel's PL/M 86 compiler. I could see the first cut could be optimized so I set about unrolling loops, getting rid of conditionals and so on. That must have been some time ago - late 70's ? Modern compilers do all that sort of thing as a matter of course - i...
by jahboater
Wed Oct 21, 2020 10:10 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

GCC isn't, and never has been, a great compiler for efficiency. Its strengths are portability, flexibility, and ubiquity. Could you please suggest a better compiler for the Pi? That is, one that generates faster code? I would be very interested. stacks off much more than it needs to for the ABI Are...
by jahboater
Wed Oct 21, 2020 2:13 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

However in these days of Python/Java/OOPS where bells and whistles are mandatory. Guy who compiles to biggest slowest, not most compact and fastest, wins. :) :) By the way, have you looked at the output from very recent GCC (10.2 is the current version) ? It would be very interesting to see an exam...
by jahboater
Wed Oct 21, 2020 1:09 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

Why are you trying to convert your C code to assembly? It's quite instructive sometimes. Yes. Very occasionally you spot when the compiler has produced a simpler or shorter solution (which will be provably correct). You can then use that to improve you own code. Or you have been worrying about some...
by jahboater
Wed Oct 21, 2020 1:05 am
Forum: General discussion
Topic: Q. Is a Raspberry Pi a good computer for internet banking / shopping?
Replies: 37
Views: 3345

Re: Q. Is a Raspberry Pi a good computer for internet banking / shopping?

ejolson wrote:
Tue Oct 20, 2020 5:40 pm
A read-only filesystem returns the system to a known state with nothing added so a person can focus on patching the original bugs that the criminal exploited without having to hunt down the back doors as well.
Work in a VM.
You may easily reset the VM after each session.
by jahboater
Wed Oct 21, 2020 12:29 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

I have to chuckle at HLL programmers who insist writing in C is just as optimized as hand assembly. No way. Sure you can find small edge cases, or SIMD code where you can beat the compiler, but for general day-to-day code, for realistic sized programs, no. Take a long hard look at the code produced...
by jahboater
Wed Oct 21, 2020 12:08 am
Forum: C/C++
Topic: Converting c code into assembly for Rasberry pi
Replies: 26
Views: 881

Re: Converting c code into assembly for Rasberry pi

How can i do with gcc S ? gcc -S -fverbose-asm -Os program.c -o program.s Choose -Os or -O3 or whatever for your optimization option. With recent versions of GCC, -fverbose-asm will intermix the original source lines with the assembler, which makes it very easy to find the interesting part of a lar...
by jahboater
Sun Oct 18, 2020 9:00 am
Forum: Advanced users
Topic: [solved] Autostart script on Raspbian Lite?
Replies: 18
Views: 559

Re: Autostart script on Raspbian Lite?

/etc/rc.local is run by systemd by the way, and is often a simpler way of running a command after boot.
(Just add your command before the final exit 0).
by jahboater
Sat Oct 17, 2020 2:02 pm
Forum: Beginners
Topic: Maximizing the lifetime of an SD card
Replies: 22
Views: 790

Re: Maximizing the lifetime of an SD card

HPCguy wrote:
Fri Oct 16, 2020 10:51 am
These are optional because tmpfs is used for swap, anyway.
Is that wise?
Swapping out memory pages to memory sounds crazy to me (unless its compressed memory - zram).
by jahboater
Sat Oct 17, 2020 2:31 am
Forum: C/C++
Topic: g++/gcc flags for different models of Pi
Replies: 5
Views: 313

Re: g++/gcc flags for different models of Pi

pi4: -mfpu=crypto-neon-fp-armv8 -march=armv8-a+crc -mcpu=cortex-a72 The Pi does not have the crypto extensions? In a makefile you can set things automatically with code like this: # # Detect hardware. # machine = $(shell sh -c 'uname -m 2>/dev/null || echo unknown') CPU = -march=native -mcpu=native...
by jahboater
Fri Oct 16, 2020 12:37 pm
Forum: General discussion
Topic: Raspberry Pi 4 Model B Not a 64 Bit ARM processor
Replies: 13
Views: 466

Re: Raspberry Pi 4 Model B Not a 64 Bit ARM processor

You are not the first to be caught out by software reporting that the CPU is something other than what one would be expecting it to be. And you probably won't be the last. It doesn't seem that situation is going to change any time soon. Perhaps its because ARM CPU's don't seem to have anything like...
by jahboater
Fri Oct 16, 2020 10:27 am
Forum: General discussion
Topic: Raspberry Pi 4 Model B Not a 64 Bit ARM processor
Replies: 13
Views: 466

Re: Raspberry Pi 4 Model B Not a 64 Bit ARM processor

I'm not sure what happens if you add "arm_64bit=1 " to config.txt, so that you are using the 64-bit kernel with a 32-bit userland. You get the same result in /proc/cpuinfo with arm_64bit=1 setting on the 32-bit OS, as you do when running the 64-bit OS. processor : 0 BogoMIPS : 108.00 Features : fp ...

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