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by jahboater
Sat Apr 23, 2016 10:57 pm
Forum: C/C++
Topic: is it possible to compile a newer gcc/ g++ on the pi itselve
Replies: 10
Views: 2811

Re: is it possible to compile a newer gcc/ g++ on the pi its

thx. just want to make sure as there's no document confirms a53 should use --with-fpu=crypto-neon-fp-armv8 and. I compiled 2 nbench for test and apparently --with-fpu=neon-vfpv4 seems to yield higher score. I cant explain the higher score. but I found that -mfpu=neon-fp-armv8 gave a better fit to t...
by jahboater
Sat Apr 23, 2016 7:04 pm
Forum: Troubleshooting
Topic: SSH question
Replies: 4
Views: 865

Re: SSH question

I am using a RPi3 and have it connected to my Macbook. I am attempting to SSH into it and have created the keys on my computer however when I use the SSH [email protected].168.2.2 it asks for a password. My question is what password is it looking for? If you have created the keys then you can use ssh-copy-id ...
by jahboater
Sat Apr 23, 2016 6:19 pm
Forum: C/C++
Topic: is it possible to compile a newer gcc/ g++ on the pi itselve
Replies: 10
Views: 2811

Re: is it possible to compile a newer gcc/ g++ on the pi its

lilunxm12 wrote:shouldn't we use --with-fpu=crypto-neon-fp-armv8 for pi3?
Yes. But its just a default.
by jahboater
Fri Apr 22, 2016 11:27 am
Forum: C/C++
Topic: Cross compiling a simple program that uses an installed lib
Replies: 7
Views: 14592

Re: Cross compiling a simple program that uses an installed

is there a special reason why you want to cross-compile and not just compile on the Pi itself, plugging a keyboard, a mouse, and a HDMI-Monitor (or a DVI Monitor plus a HDMI Adapter) ? Yes! Have you tried a Pi3? Its pretty fast, and capable of building almost anything (such as the Linux kernel or G...
by jahboater
Fri Apr 22, 2016 10:05 am
Forum: Troubleshooting
Topic: Float value inaccuracies - how to trace?
Replies: 3
Views: 752

Re: Float value inaccuracies - how to trace?

I don't know how your floats are being stored, but x86 machines may use 80-bits precision (64 bit significand), the ARM/VFP/NEON will only be 64-bits (53-bit significand).
by jahboater
Fri Apr 22, 2016 9:59 am
Forum: Troubleshooting
Topic: RPI3, NOOBS OK, Raspian NOK
Replies: 3
Views: 653

Re: RPI3, NOOBS OK, Raspian NOK

That's good news.

The .img file overwrites everything, there is never any need to partition or format the card first.
by jahboater
Fri Apr 22, 2016 9:43 am
Forum: General discussion
Topic: Raspberry pi 3, its limitations
Replies: 9
Views: 5956

Re: Raspberry pi 3, its limitations

They are all free, so why don't you get a couple of SD cards and try them?
8GB cards suffice and are very cheap.
by jahboater
Fri Apr 22, 2016 9:38 am
Forum: Beginners
Topic: Why does Kali seem faster/better than Rasbian to me?
Replies: 3
Views: 936

Re: Why does Kali seem faster/better than Rasbian to me?

Use this to measure boot time:-

Code: Select all

systemd-analyze
Add the argument "blame" to get more details.
Are both your SD cards identical?

Raspbian is stable as a rock for me.
Can you give an example of something that crashes?
by jahboater
Thu Apr 21, 2016 6:33 pm
Forum: Bare metal, Assembly language
Topic: Act LED (hello world)' Programming on RPi 3 (BCM2837)
Replies: 19
Views: 7850

Re: Act LED (hello world)' Programming on RPi 3 (BCM2837)

The on-board LEDs are not meant to be controlled by the user... the red LED is a power indicator, while the green LED is an SD card read|write activity indicator. They were rather good on the Pi2 ... [email protected]:/sys/class/leds/led0 $ cat trigger none [mmc0] mmc1 timer oneshot heartbeat backligh...
by jahboater
Thu Apr 21, 2016 7:10 am
Forum: Beginners
Topic: NEW SD CARD
Replies: 8
Views: 1274

Re: NEW SD CARD

Or try installing the Raspbian OS image directly - there is no need to format the disk first, and Raspbian itself can deal with any sized disk.
https://www.raspberrypi.org/downloads/raspbian/
by jahboater
Thu Apr 21, 2016 6:28 am
Forum: General discussion
Topic: RPi 3 composite does not work
Replies: 11
Views: 3952

Re: RPi 3 composite does not work

Yes, you do want hdmi... in my opinion the designers should not have included composite video on the card (but that´s another story). The only reason for the composite video output is for those cases where there´s an antique TV laying around a kid can get his Raspberry PI working without having to ...
by jahboater
Thu Apr 21, 2016 6:15 am
Forum: General discussion
Topic: Why Is wolfram-engine included?
Replies: 35
Views: 17936

Re: Why Is wolfram-engine included?

You know, rather than getting worked up about Wolfram, seeing it as the villain in wasting your day, you could ponder why you didn't spend just a few dollars more to get a MicroSD card that was twice as big to begin with. ;) A 16 GB card doesn't cost much, and has loads of free space beyond the def...
by jahboater
Wed Apr 20, 2016 7:24 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3 - No audio
Replies: 9
Views: 4749

Re: Raspberry Pi 3 - No audio

Is no one actually reading my posts? The OS will not let me make root level changes. The folder the config.txt file is in has root level write permission and won't let me overwrite the file or even save a copy of it there. The sudo prefix does not work nor will any command entered on the command li...
by jahboater
Tue Apr 19, 2016 4:43 pm
Forum: Beginners
Topic: How does some one become a competent programmer?
Replies: 73
Views: 10384

Re: How does some one become a competent programmer?

W. H. Heydt wrote: When I was in college, C didn't exist, let alone C++.
Ditto, but we did have its predecessor B and used it to get things done.
Otherwise it was Fortran IV, Pascal, COBOL, Lisp, the Algols etc.
It was a long time before I got to use C.
by jahboater
Mon Apr 18, 2016 3:01 pm
Forum: Advanced users
Topic: Modifying raspbian
Replies: 5
Views: 856

Re: Modifying raspbian

RaTTuS wrote:edit the correct config.txt
change ...
Did you mean cmdline.txt?
by jahboater
Sun Apr 17, 2016 8:54 pm
Forum: C/C++
Topic: C programming Language before C++
Replies: 19
Views: 2672

Re: C programming Language before C++

Code: Select all

sudo apt-get install gcc-4.9-doc
Then "man gcc" tells all.

I have a feeling the OP simply wants "C" instead of "C++".
by jahboater
Sun Apr 17, 2016 8:24 pm
Forum: C/C++
Topic: C programming Language before C++
Replies: 19
Views: 2672

Re: C programming Language before C++

Can you specify to gcc that you want a specific version of C to be used? I thought that was possible. Whether you can make it go back that far I don't know. You can go back as far as C89 (iso9899:1990) which is later than K&R. (-std=c89). There is also -std=c99 and the default which is -std=c11, th...
by jahboater
Sun Apr 17, 2016 8:15 pm
Forum: C/C++
Topic: C programming Language before C++
Replies: 19
Views: 2672

Re: C programming Language before C++

Do you mean C (instead of C++) or do you mean an early version of C?

If you could say why, it might help too.
by jahboater
Sat Apr 16, 2016 9:55 am
Forum: Beginners
Topic: How does some one become a competent programmer?
Replies: 73
Views: 10384

Re: How does some one become a competent programmer?

YeYaaa ... REXX, luv it ... we should start an (ex)IBM employee's thread ;-) ... three members and counting. I really really loved REXX but didn't actually work for IBM. Just used VM/CMS, and interestingly UNIX (UTS) in a VM, for a few years as a systems programmer. The question is, what will you d...
by jahboater
Thu Apr 14, 2016 2:17 pm
Forum: Troubleshooting
Topic: Win32diskimager stopped during writing
Replies: 12
Views: 2239

Re: Win32diskimager stopped during writing

During the installation I first formatted the SD card using SDFormatter and I tried to write the image to the SD card. After a while (I do not remember it exactly, but it was around the 10%) the win32diskimager gives an error and stopped writing. The OP is trying to use win32diskimager, so all this...
by jahboater
Thu Apr 14, 2016 12:33 pm
Forum: Troubleshooting
Topic: Win32diskimager stopped during writing
Replies: 12
Views: 2239

Re: Win32diskimager stopped during writing

When trying to format the SD card in Pi, was it in the normal SD card socket on the Pi? or in a separate USB card reader? The former will most definitely not work. To install a Raspbian image you do not have to format the card first. Writing the image to the card will overwrite any contents, any par...
by jahboater
Thu Apr 14, 2016 7:59 am
Forum: General discussion
Topic: Raspberry Pi 3 and O.S. drive.
Replies: 5
Views: 1398

Re: Raspberry Pi 3 and O.S. drive.

The Pi3 can boot from a USB disk, but the firmware is not ready yet. Using SD cards was an inspired design decision. They are tiny, cheap, and silent, like the Pi itself. Just like any SSD, there are various well known ways to reduce writes to the card, ultimately (as described above), using it only...
by jahboater
Thu Apr 14, 2016 7:40 am
Forum: C/C++
Topic: Differentiate RPi from other SBCs using compiler flags/etc
Replies: 2
Views: 725

Re: Differentiate RPi from other SBCs using compiler flags/e

This file, if it exists, contains a nul terminated string starting with Raspberry Pi.

Code: Select all

/sys/firmware/devicetree/base/model
by jahboater
Thu Apr 14, 2016 7:32 am
Forum: Advanced users
Topic: Changing the behaviour of cleaning tmp-files
Replies: 3
Views: 932

Re: Changing the behaviour of cleaning tmp-files

How about mounting /tmp as tmpfs (in memory). That way it gets cleaned out automatically with every reboot. Save a bit of wear on the card too.
Add something like this to /etc/fstab

Code: Select all

tmpfs /tmp  tmpfs defaults,noatime 0 0
tmpfs /var/log  tmpfs defaults,noatime,size=64m 0 0
by jahboater
Thu Apr 14, 2016 7:17 am
Forum: Troubleshooting
Topic: Imaging problem to a micro-SDcard
Replies: 10
Views: 2892

Re: Imaging problem to a micro-SDcard

Disks which are nominally the same size often vary slightly in their actual size. If the target disk is smaller the imaging will fail, even if its only a tiny bit smaller. One solution is to shrink the partition on the source disk such that it will fit on any target disk. As noted above, using the s...

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