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by jahboater
Mon Oct 26, 2020 5:36 pm
Forum: Troubleshooting
Topic: editor says program installed can't run or find
Replies: 8
Views: 263

Re: editor says program installed can't run or find

jsixis wrote:
Mon Oct 26, 2020 5:15 pm
What am I missing here?
You are getting mixed up between an editor (such as vi, nano, emacs, gedit, leafpad etc) and a terminal window.
An editor is used for altering or writing text, while a terminal window is for entering commands, usually into something called a shell.
by jahboater
Mon Oct 26, 2020 12:14 pm
Forum: C/C++
Topic: Pi 4 + Ubuntu 20.10 (64bit) - compiling into 64-bit architecture
Replies: 2
Views: 354

Re: Pi 4 + Ubuntu 20.10 (64bit) - compiling into 64-bit architecture

Looks like you have a 32-bit armv7 compiler which is surprising on your 64-bit OS. Did you build it yourself? On Raspberry Pi OS 64 I get: long int: 8 size_t: 8 void*: 8 My compiler is configured: $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/aarch64-unkno...
by jahboater
Sun Oct 25, 2020 8:53 pm
Forum: Troubleshooting
Topic: Raspberry Pi 4 temperature
Replies: 601
Views: 343065

Re: Raspberry Pi 4 temperature

The best thing is to get a heat sink without sticky back, and mount it with thermal paste. For as long as the unit is kept horizontal, the thermal paste will keep the sink in place. This heatsink from RS is 3.5K/W and has no tape: https://uk.rs-online.com/web/p/heatsinks/6744835/ this one is 8.2K/W...
by jahboater
Sun Oct 25, 2020 2:54 pm
Forum: Java
Topic: java is not supported any more on Pi0 with OS buster
Replies: 13
Views: 12717

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

Presumably you were trying to build some code written to a nightly build, basically a beta of a future release, which used features not yet available in the stable release. Yes, I guessed it was something like that. It was your code. People tried the Rustc from apt-get and it failed for some reason...
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: 12717

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: 280

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: 14
Views: 597

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: 455

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: 348

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: 1314

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: 14
Views: 597

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: 646

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: 198

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: 1314

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: 1164

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: 1164

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: 1164

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: 1164

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: 1164

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: 1164

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: 40
Views: 3762

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: 1164

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: 1164

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: 633

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).

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