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by swampdog
Wed Dec 11, 2019 6:20 pm
Forum: Troubleshooting
Topic: SD boot with USB root - kernel boot does not see USB device
Replies: 4
Views: 118

Re: SD boot with USB root - kernel boot does not see USB device

No, you do not need an initrd unless you do something exotic like use LVM. There might be a tool to do what you want. I can't remember because I haven't used it. Someone else will post to verify, I'm sure. I installed to an sdcard then with the system running, created the partition on the usb disk, ...
by swampdog
Wed Dec 11, 2019 5:23 pm
Forum: Advanced users
Topic: SSH with RSA keys for MPI cluster
Replies: 4
Views: 146

Re: SSH with RSA keys for MPI cluster

This post is a little over a month old, but I'll toss my 2cents in. I don't think that there is a way around having to supply credentials at east once. Not on a live system (although sshpass might work if you pass some options to scp so it doesn't ask questions). If you're writing the image to go o...
by swampdog
Wed Dec 11, 2019 10:58 am
Forum: Troubleshooting
Topic: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)
Replies: 11
Views: 549

Re: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)

I doubt fragmentation would be an issue. Might still be worth plugging it into your PC. Raspbian: foo@pi18:/wrk $ chmod u+x z.sh && cat z.sh && ./z.sh #!/bin/bash C=2097152 D="/wrk" dd if=/dev/urandom of="$D"/z bs=1024 count="$C" status=progress echo "^^^ignore timing here 'cos of urandom" time (rm ...
by swampdog
Wed Dec 11, 2019 9:48 am
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

He is playing mental hijinx where something like Circle isn't an O/S because it doesn't have apps, some sort of console to launch them and so on and whatever rubbish your swampdog O/S definition says. Circle is more like an RTOS which most of us would still call an O/S but not swampdog it fails his...
by swampdog
Tue Dec 10, 2019 3:34 pm
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

I'm trying to get the OP to define what he means. We could debate what the wiki says there but methinks all we'd end up doing is going round in circles defining what an operating system is. To me you are the one going in circles, so lets just define it as like circle (a pun) from rst that is an ent...
by swampdog
Tue Dec 10, 2019 2:52 pm
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

Swampdog, ...my idea of an embedded system is one which has no operating system... Which is not the commonly accepted meaning in the industry. Which is more like what you read here: https://en.wikipedia.org/wiki/Embedded_system I have worked on embedded systems that were far bigger than a micro-con...
by swampdog
Tue Dec 10, 2019 6:17 am
Forum: Troubleshooting
Topic: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)
Replies: 11
Views: 549

Re: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)

And executed a long test: pi@raspberrypi3:~ $ sudo smartctl -t long /dev/sdc -d sat smartctl 6.6 2017-11-05 r4594 [armv7l-linux-4.19.75-v7+] (local build) Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org === START OF OFFLINE IMMEDIATE AND SELF-TEST SECTION === Sending com...
by swampdog
Mon Dec 09, 2019 8:47 pm
Forum: Troubleshooting
Topic: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)
Replies: 11
Views: 549

Re: Random speed slowdown reading files from connected usb hard drive on rpi3 (not a network problem)

This is more usual output from smartctl.. foo@pi19:~ $ lsscsi [0:0:0:0] disk asmedia ASMT1153e 0 /dev/sda [1:0:0:0] disk JMicron Tech 0203 /dev/sdb [2:0:0:0] disk JMicron Tech 0203 /dev/sdc [3:0:0:0] disk JMicron Tech 0203 /dev/sdd foo@pi19:~ $ sudo smartctl -a /dev/sdd smartctl 6.6 2017-11-05 r4594...
by swampdog
Mon Dec 09, 2019 12:02 pm
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

I am following same approach I want to write embedded program using OOP concept. If we remove oop concept in c++, then c++ is same as c. My focus is to write a embedded program with OOP. My question Have you used inheritance in real time project. Can you tell me with few lines why did you think you...
by swampdog
Mon Dec 09, 2019 10:44 am
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

swampdog, The switches seemed too complex. They might arc.... Indeed. But switches need not be electrical. I have worked on control systems with a lot of hydraulic switches. Spool valves. It's amazing what logic you can do with those. Then you have issues of fluid pressure and so on. I have also bu...
by swampdog
Sun Dec 08, 2019 10:38 pm
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

swampdog, Oh boy. That is a thing. You have introduced a hundred other concepts besides "switch". Volts, amps, batteries, lamps, the whole circuit simulation! The switches seemed too complex. They might arc. You'd need to take electromagnetic interference into account so there'd be a "radio broadca...
by swampdog
Sun Dec 08, 2019 9:57 pm
Forum: C/C++
Topic: Simple example of class and object
Replies: 27
Views: 674

Re: Simple example of class and object

An electronics example is actually quite a tough one to start with because there will lots of hidden things depending on how much detail is required. I also haven't done analog electronics for nearly 4 decades! Using the first diagram from the link you provided here's a rough template.. #include <io...
by swampdog
Sat Dec 07, 2019 6:14 pm
Forum: C/C++
Topic: Qt Creator 4.10.0
Replies: 2
Views: 193

Re: Qt Creator 4.10.0

I was away for longer than I thought! It may be you have to uninstall some stuff though I suspect not. I started with a standard raspbian desktop image (not lite, not full) so whilst there's a handful of qt5 system libs there are not too many. I had already built it under linux mint 18 so had an ide...
by swampdog
Fri Nov 29, 2019 11:40 pm
Forum: C/C++
Topic: Qt Creator 4.10.0
Replies: 2
Views: 193

Qt Creator 4.10.0

I'm away until early/mid next week and am about to set off what should be an error free build of QT 5.12.5 on rpi4. Just wanted to see if there's any interest. It'll be a big tarball (approx 3Gb). It will contain this.. gcc 9.2.0 cmake 3.15.4 mariadb 10.4.8 z3 4.8.6 llvm 8.0.1 cfe 8.0.1 lld 8.0.1 qt...
by swampdog
Fri Nov 29, 2019 10:34 pm
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

vgchange -a y courante pvmove -i 15 What happened? jlee@courante:~ $ sudo vgchange -a y courante device-mapper: reload ioctl on (253:17) failed: Input/output error # dmsetup ls --tree Output? ..the one matching 253:17 is the bad device (LV). I'm afraid I'm away until next week. You can try to "lvch...
by swampdog
Fri Nov 29, 2019 10:37 am
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

Hello, I guess I did not make myself clear in the original post. I am using lvm raid5 volume for /home, by using lvconvert --type raid5 to convert a linear volume into raid5. The following is what I get from lvs command. root@courante:~# lvs -a -o +devices LV VG Attr LSize Pool Origin Data% Meta% M...
by swampdog
Fri Nov 29, 2019 10:01 am
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

The first thing to do would be to try and recover the mdadm RAID array. Then look at resuming the pvmove. We'll have to wait for the OP. I'm not sure there is a software raid.. [ 15.565790] device-mapper: raid: Failed to read superblock of device at position 2 [ 15.601120] md/raid:mdX: not clean --...
by swampdog
Fri Nov 29, 2019 8:39 am
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

I'll admit I've never used LVM RAID by itself. I've always used LVM on top of MD which handled the RAID side of things. Yep. It's unusual. I've just found some info on redhat site. Since rhel 6.3 the default changed away from "segment type mirror" to "segment type raid1" so it will depend what inst...
by swampdog
Fri Nov 29, 2019 7:54 am
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

Do not use raid5. It needs four drives and only one can fail. RAID 5 requires a minimum of three drives of which at least two need to be operational for the data to be accessible. Depending how LVM is configured an extra drive may be required for logging (--mirrorlog). I'm playing it safe because w...
by swampdog
Fri Nov 29, 2019 6:05 am
Forum: Raspbian
Topic: lvm: pvmove crashed, how to recover?
Replies: 12
Views: 235

Re: lvm: pvmove crashed, how to recover?

My system consists of rasberry pi 4 with raspian using the 64bit kernel I'd suspect the 64bit kernel.. [ 9667.686238] INFO: task usb-storage:176 blocked for more than 120 seconds. ..or your usb adapter. I'm afraid if you really wanted this data you should have not gone bleeding edge and done more t...
by swampdog
Thu Nov 28, 2019 2:57 am
Forum: Networking and servers
Topic: AM I defaulting to a degraded Raid5 array?
Replies: 16
Views: 471

Re: AM I defaulting to a degraded Raid5 array?

Deathstars? I guess you could call contracting for a public body a deathstar. :-) rpdom is talking about the disasterous IBM Deskstar hard disks from around 2000. One particular HD had an incredibly high failure rate and caused the name IBM Deathstar to be coined. If your HD died then it was disast...
by swampdog
Thu Nov 28, 2019 2:24 am
Forum: C/C++
Topic: Linaro armv8l-linux-gnueabihf compiler
Replies: 2
Views: 147

Re: Linaro armv8l-linux-gnueabihf compiler

Nothing obvious looking at the linaro website so you'll probably have to look at the source for the configs. This *might* help..

Code: Select all

gcc -v --help 2>&1 | less
gcc -march=native -Q --help=target | less
..replacing 'gcc' accordingly.
by swampdog
Thu Nov 28, 2019 1:56 am
Forum: C/C++
Topic: Raspi 4b reserve core for C++
Replies: 30
Views: 922

Re: Raspi 4b reserve core for C++

Can't remember how to use it but here you go.. admin@pi05:~ $ apropos affinity pthread_attr_getaffinity_np (3) - set/get CPU affinity attribute in thread at... pthread_attr_setaffinity_np (3) - set/get CPU affinity attribute in thread at... pthread_getaffinity_np (3) - set/get CPU affinity of a thre...
by swampdog
Thu Nov 28, 2019 1:50 am
Forum: Networking and servers
Topic: AM I defaulting to a degraded Raid5 array?
Replies: 16
Views: 471

Re: AM I defaulting to a degraded Raid5 array?

rpdom wrote:
Wed Nov 27, 2019 6:19 am
swampdog wrote:
Wed Nov 27, 2019 2:59 am
Last reasonably big place I worked at, it was the "nobody ever got sacked for buying ibm" mantra.
Deathstars?
I guess you could call contracting for a public body a deathstar. :-)
by swampdog
Wed Nov 27, 2019 3:33 am
Forum: Raspbian
Topic: Multiple rpi3 gone offlien on the lan at the same minute definitively
Replies: 3
Views: 153

Re: Multiple rpi3 gone offlien on the lan at the same minute definitively

I would check the dhcp lease first. $ sudo cat /var/log/syslog | egrep -i dhcp ..possibly "syslog.1" or older files. Also check your dhcp server logs - as everything went wrong at the same time it was probably that which caused the problem. For example, when my ISP does a firmware update on our cabl...

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