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by jahboater
Sat Dec 04, 2021 4:43 am
Forum: Beginners
Topic: System? where's the system
Replies: 7
Views: 349

Re: System? where's the system

kerry_s wrote:
Sat Dec 04, 2021 1:48 am
if your running a full desktop os, yes it would have that.
raspberry os doesn't.
And why isn't Rasperry Pi OS a full desktop OS? (apart from the Lite version that is).
by jahboater
Fri Dec 03, 2021 6:59 pm
Forum: General discussion
Topic: What is the size of the included sd card?
Replies: 16
Views: 847

Re: What is the size of the included sd card?

if so, what enables it the best? Leaving half of the card unpartitioned, or using the whole card for the rootfs and making sure not to use the entire file system so that the ext4 partition is at least half empty? I suspect as far as the card's controller is concerned it would make no difference? I ...
by jahboater
Fri Dec 03, 2021 12:04 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3B+ Bullseye Performance is Unacceptable [actually Pi1]
Replies: 30
Views: 1029

Re: Raspberry Pi 3B+ Bullseye Performance is Unacceptable [actually Pi1]

This command shows swap, block I/O etc.

Code: Select all

vmstat 10
prints details every ten seconds.
by jahboater
Fri Dec 03, 2021 10:54 am
Forum: SDK
Topic: Mixing C with Assembly code
Replies: 10
Views: 422

Re: Mixing C with Assembly code

Regarding flags, is there also a way now to handle carry in C (e.g. for multi-word shift operations ? ) Do you mean pure C, or C with inline assembler? The carry flag is available from assembler in the same way as the overflow flag in the example above. For basic arithmetic (add, subtract, multiply...
by jahboater
Thu Dec 02, 2021 6:48 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3B+ Bullseye Performance is Unacceptable [actually Pi1]
Replies: 30
Views: 1029

Re: Raspberry Pi 3B+ Bullseye Performance is Unacceptable

I have no idea where you found a Pi1 and bought it - the recommendation from absolutely everyone is always get the latest version. Sounds like the OP thought they had purchased a 3B+ but was actually sold a Pi1. Perhaps the supplier needs investigating. cat /proc/device-tree/model; echo The Pi1 is ...
by jahboater
Thu Dec 02, 2021 10:03 am
Forum: SDK
Topic: Mixing C with Assembly code
Replies: 10
Views: 422

Re: Mixing C with Assembly code

As said before, comments / improvements are welcome. In most cases, doing assemble snippets in asm... statements in the C code (often useful as Macros) makes sense, avoiding the necessary of an ABI compliant call...return, and allowing the compiler to do better optimization. -Michael +1 definitely ...
by jahboater
Thu Dec 02, 2021 3:10 am
Forum: General discussion
Topic: Constant CPU speed?
Replies: 6
Views: 349

Re: Constant CPU speed?

cleverca22 wrote:
Thu Dec 02, 2021 1:02 am
userspace lets you echo a number into scaling_setspeed to change the freq to whatever you want
This works and doesn't need a reboot.
Thanks, that's a new one!
by jahboater
Thu Dec 02, 2021 3:05 am
Forum: Advanced users
Topic: Does Anyone Have any Compiling Tips
Replies: 20
Views: 697

Re: Does Anyone Have any Compiling Tips

hippy wrote:
Wed Dec 01, 2021 11:42 pm
dickon wrote:
Wed Dec 01, 2021 8:36 pm
ncx wrote:
Wed Dec 01, 2021 8:16 pm
I wouldn't consider swap as RAM.
I would: it's just very slow RAM[0].
I wouldn't. But each to his own.
Its all virtual memory, and apart from speed, should be indistinguishable to programs.
by jahboater
Wed Dec 01, 2021 6:58 pm
Forum: Advanced users
Topic: Does Anyone Have any Compiling Tips
Replies: 20
Views: 697

Re: Does Anyone Have any Compiling Tips

An 8GB Pi4 works too, running the 64-bit OS ...
by jahboater
Wed Dec 01, 2021 5:57 pm
Forum: General discussion
Topic: Constant CPU speed?
Replies: 6
Views: 349

Re: Constant CPU speed?

Actually, arm_freq_min only sets the minimum clock speed for dynamic frequency clocking . The clock frequency is still variable, it just won't fall below the set value. Yes, that's true. However if you set it to the same as the maximum, then the clock speed stays the same all the time regardless of...
by jahboater
Wed Dec 01, 2021 10:11 am
Forum: General discussion
Topic: Constant CPU speed?
Replies: 6
Views: 349

Re: Constant CPU speed?

I'd like to run my Raspberry Pi (3b+) ARM Cortex A53 processor on a **constant** CPU speed. It can be the lowest one, doesn't matter, as long as it does not change. Would that be possible to set up on Raspbian? Yes, on Raspberry Pi OS: For example, in /boot/config.txt arm_freq=1000 arm_freq_min=1000
by jahboater
Tue Nov 30, 2021 2:50 pm
Forum: C/C++
Topic: Compiled code on amrv7l do no longer run on armv6l since PiOS 11
Replies: 29
Views: 855

Re: Compiled code on amrv7l do no longer run on armv6l since PiOS 11

jamesh wrote:
Tue Nov 30, 2021 2:02 pm
Hmm, odd one. Will flag it to appropriate dev.
Looks like its failing because its trying to do a movw/movt which (I vaguely remember is not in armv6) in the C startup code (before it gets to main).
by jahboater
Tue Nov 30, 2021 1:53 pm
Forum: C/C++
Topic: Compiled code on amrv7l do no longer run on armv6l since PiOS 11
Replies: 29
Views: 855

Re: Compiled code on amrv7l do no longer run on armv6l since PiOS 11

It doesn't work with -march=armv6zk -mcpu=arm1176jzf-s either.

The GCC compiler on the Pi Zero works very well by the way.
For small programs less than a 1000 lines or so, it should be fast enough.
by jahboater
Mon Nov 29, 2021 10:24 am
Forum: General programming discussion
Topic: Which language has the widest RP support?
Replies: 5
Views: 248

Re: Which language has the widest RP support?

Please don't link bad articles that just talk about every programming language and how C++ is a difficult language because it has classes. C++ is not a terrible language because it has classes. In fact the C++ guys tend to play down object oriented programming now a days. C++ has many, many other w...
by jahboater
Sun Nov 28, 2021 10:51 am
Forum: SDK
Topic: [SOLVED] Coercing a number to string literal
Replies: 17
Views: 434

Re: [SOLVED] Coercing a number to string literal

I know its not directly what you want, but for interest, the library and compiler use things like this:

Code: Select all

#define __GLIBC_PREREQ(maj,min) ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min)
so you can use:

Code: Select all

#if __GLIBC_PREREQ(2,25)
Might be useful at some point.
by jahboater
Sat Nov 27, 2021 11:02 pm
Forum: Advanced users
Topic: What would be considered as a good / modest overclock speed?
Replies: 12
Views: 582

Re: What would be considered as a good / modest overclock speed?

This looks like a pretty nice case. What os does your Raspberry Pi use and what are your pi's temperatures with this case? Raspberry Pi OS 64-bit. Here is a temperature log. At 22:50 I started all four CPU cores running flat out, you can see the frequency jump up to 2.1GHz. Throttling starts at 85C...
by jahboater
Sat Nov 27, 2021 6:21 pm
Forum: Advanced users
Topic: What would be considered as a good / modest overclock speed?
Replies: 12
Views: 582

Re: What would be considered as a good / modest overclock speed?

My heavily used Pi4 is in one of these:
https://thepihut.com/products/aluminium ... berry-pi-4

This Pi4 runs very cool at 2.1GHz and never comes close to throttling under any workload.

There are many other "heatsink" cases.
by jahboater
Sat Nov 27, 2021 12:28 am
Forum: C/C++
Topic: Why no warning?
Replies: 46
Views: 1916

Re: Why no warning?

With GCC and Clang you can use -ftrapv to fail signed integer overflow, there is no need to artificially "undefine" it. See also -fwrapv which only GCC supports. -ftrapv This option generates traps for signed overflow on addition, subtraction, multiplication operations. -fwrapv This option...
by jahboater
Fri Nov 26, 2021 8:54 am
Forum: C/C++
Topic: Why no warning?
Replies: 46
Views: 1916

Re: Why no warning?

"int to float" always gives reasonable results. The least significant few bits might get dropped if the number is large, but it will still be sensible. An extreme example: INT64_MAX (92233720368547758 07 ) gets converted to 9.2233720368547758e+18 which is very close. "float to int&quo...
by jahboater
Thu Nov 25, 2021 7:30 pm
Forum: General discussion
Topic: STICKY: Raspberry Pi OS (64 bit) beta test version feedback
Replies: 1003
Views: 266125

Re: STICKY: Raspberry Pi OS (64 bit) beta test version feedback

jamesh wrote:
Fri Nov 19, 2021 1:11 pm
16GB would be OK for a headless machine I suspect.
It is OK. Buster or bullseye, 32 or 64 bits.
by jahboater
Thu Nov 25, 2021 7:07 pm
Forum: Raspberry Pi OS
Topic: STICKY: Bullseye - Comments and bug reports thread.
Replies: 488
Views: 27368

Re: STICKY: Bullseye - Comments and bug reports thread.

AleXSR700 wrote:
Thu Nov 25, 2021 6:58 pm
When will Raspberry finally make the 64-bit an official option rather than having people look for it in the depths of github?
The 64-bit Raspberry Pi OS images are here:
https://downloads.raspberrypi.org/
I never get them from github.
by jahboater
Thu Nov 25, 2021 7:05 pm
Forum: Beginners
Topic: Raspberry Pi OS - which to choose? Lite, w/Desktop or Recommended
Replies: 8
Views: 320

Re: Raspberry Pi OS - which to choose? Lite, w/Desktop or Recommended

bjtheone wrote:
Thu Nov 25, 2021 6:45 pm
The basics are Lite + X11 + Desktop Manager, and is a simple "sudo apt install package_name" process....
Isn't Linux wonderful!
If you don't like the Windows desktop, what are you supposed to do?

Sorry for off-topic post.
by jahboater
Thu Nov 25, 2021 6:47 pm
Forum: General discussion
Topic: What is the size of the included sd card?
Replies: 16
Views: 847

Re: What is the size of the included sd card?

Plus the main reason... 16GB namebrand (I choose SanDisk for this exercise): 16 GB for $10.99, 32 GB for $12.49 (as per Amazon Canada). Amazon UK has different pricing. The Sandisk Extreme cards I buy are 16GB (not available), 32GB £10.35, 64GB £9.99, 128GB £16.99 64GB seems a no-brainer! Using a l...
by jahboater
Thu Nov 25, 2021 9:41 am
Forum: C/C++
Topic: Why no warning?
Replies: 46
Views: 1916

Re: Why no warning?

Heater, The issue, for me at least, is silent conversion of integers to floats and the potential inaccuracies introduced. I mentioned before that the floating-point exception status flags are cumulative ("sticky"). Unlike the integer flags which are lost almost immediately, these have to b...
by jahboater
Thu Nov 25, 2021 6:18 am
Forum: Networking and servers
Topic: Sending commands over the internet
Replies: 8
Views: 278

Re: Sending commands over the internet

Try ssh.

ssh pi@host command(s)

If a remote program needs the screen (such as an editor) then give the -t option
For example:

ssh -t pi@host 'sudo vi /boot/config.txt'

Best to set up password less authentication.

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