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119 votes
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is my linux ARM 32 or 64 bit?

There are several gradations, since you can run a 32-bit or mixed operating system on a 64-bit-capable CPU. See 64-bit kernel, but all 32-bit ELF executable running processes, how is this? for a ...
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59 votes
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Porting Linux to another platform requirements

Even though most of the code in the Linux kernel is written in C, there are still many parts of that code that are very specific to the platform where it's running and need to account for that. One ...
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57 votes

Is it possible to get the information for a device tree using /sys of a running kernel?

/proc/device-tree or /sys/firmware/devicetree/base /proc/device-tree is a symlink to /sys/firmware/devicetree/base and the kernel documentation says userland should stick to /proc/device-tree: ...
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33 votes

disabling cpu cores on quad core processor on linux

As Patrick has indicated in a comment, you got the path under /sys wrong. echo 0 > /sys/devices/system/cpu/cpu3/online If you want to switch all CPUs off except cpu0: for x in /sys/devices/...
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31 votes

is my linux ARM 32 or 64 bit?

As richard points out, armv7 variants are all 32-bit, so there is no redundant label armv7-32, etc. On a linux system, you can easily, although not truly definitively, check by examining a common ...
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30 votes

How to use /dev/fb0 as a console from userspace, or output text to it

Several people have answered the parts of your question dealing with the kernel and putting images (rather than text) onto the framebuffer, but so far the rest remains unaddressed. Yes, you can use ...
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  • 62.4k
20 votes

Install 64 bit programs on a 32 bit OS with a 64 bit processor

Is it possible to install a 64 bit program on a 32 bit OS with a 64 bit processor? In principle yes, but the processor and the OS have to support it. On ARMv8, a 32-bit (Aarch32) kernel cannot run ...
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18 votes

What is the difference between different implemetation of arm64/aarch64 for Linux or other software to run on?

Your question could be interpreted as pretty broad, but I think what you're actually asking about is extremely specific. The fundamental difference between the different implementations of arm64 vs. ...
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16 votes

How to use /dev/fb0 as a console from userspace, or output text to it

If you can cat /dev/urandom > /dev/fb0 and get random pixels on the screen, you have all you need. In my case I needed to dump some text info. I tested this in busybox and raspi, so it might work ...
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  • 161
16 votes

Running X86 binaries on armv7

You can't easily convert an x86 binary to ARM. If you can't get the source code, or an ARM binary from the manufacturer, and you really do want to use the printer with your Pi2, then the Qemu approach ...
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15 votes

is my linux ARM 32 or 64 bit?

Install the 'lshw' package. # lshw ... description: Computer product: Raspberry Pi 3 Model B Rev 1.2 width: 32 bits ...
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  • 151
15 votes
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How do I cross-compile Chromium for ARM?

Now that I'm at work, I'll write up a step by step answer. First off you seem to be doing the steps in the wrong order. As such, I'll number these steps in the order they should be executed. mkdir -...
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  • 5,603
13 votes

is my linux ARM 32 or 64 bit?

Seems like most ways to see bit count is to somehow know that arm7=32 bit and while that may be true but what about pi@rpi9:~ $ getconf LONG_BIT 32 And if you want to look for the cpu model I ...
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  • 531
13 votes

list all components of an ARM computer in Linux?

The variation of ARM implementations is too high to be covered with the standard tools. Digging down /sys/class you will find all your components, but it's a pain to do so. You can't use find /sys/...
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  • 11.7k
12 votes

Linker script in .so file? (libc.so) Is that right?

When you see a file named .so, it’s not necessarily a shared library. These files are used when linking a program at build-time, not run-time; they are commonly symlinks to the real shared library, ...
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11 votes

What do the flags in /proc/cpuinfo mean?

x86 Find it yourself in 4.1.3 x86 and the Intel manual arch/x86/include/asm/cpufeature.h contains the full list. The define values are of type: X*32 + Y E.g.: #define X86_FEATURE_FPU ( 0*32+ ...
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11 votes
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QEMU with KVM with differing host/guest architectures

The naive way to run a virtual machine is to interpret each instruction. The VM software decodes each instruction and runs it. When the instruction set of the virtual machine is the same as the host, ...
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11 votes

Porting Linux to another platform requirements

In addition to porting the Linux kernel, you will need to define the application binary interface (ABI) for "user space" programs and port the lowest layers of the user space software stack. Linux is ...
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10 votes

What do the flags in /proc/cpuinfo mean?

Or alternatively you can use cpuid program, it must be in debian repository. It dumps every possible info about your CPU with some explanations, so you don't get those obscure flags.
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  • 317
10 votes

What does armel stand for?

el stands for little-endian; see the email explaining (briefly) the decision; the follow-up emails contain more information. Endianness isn't the most distinguishing feature of armel, but that's the ...
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8 votes
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Cross compiling GLIBC for my ARM SoC

I made it :-) I basically followed Gilles's advice and decided to do it properly: i.e. manage a complete cross-compilation of GLIBC. I started from crosstool-ng, and was initially disappointed - ...
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  • 2,189
8 votes

Meaning of an ampersand prefix in a device tree

From: http://developer.toradex.com/device-tree-customization Nodes can be referenced using the ampersand (&) character and the label. Overwriting properties To overwrite a property, the node ...
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  • 527
8 votes

list all components of an ARM computer in Linux?

For listing hardware in IoT devices, usually the most useful commands after dmesg are cat /proc/cpuinfo and lsusb. In most IoT brands, lsusb reveals itself useful, as for instance sinovoip (banana) ...
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7 votes
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How do determine whether Linux board is using hardware FPU or not?

In the ARM world from ARMv4 to ARMv7 floating-point support is called VFP, and hardware support for it appears in the Features line of /proc/cpuinfo or in the VFP support log message printed by the ...
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7 votes

Why does typing "./" in sh produce "permission denied"?

If I were to guess, your sh favours simplicity or performance over user friendliness. The "permission denied" error is that provided by perror(3), a standard function for printing an error message. ...
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  • 64.3k
7 votes

How to uniquely identify ARM devices without relying on MAC-address?

Get the serial of the device from /proc/cpuinfo grep Serial /proc/cpuinfo Serial : 1651660a0642ebb0 (taken from my A20 based SoC, Lamobo R1 aka Banana Pi R1 and ArmBian/Jessie with kernel 4.5....
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7 votes
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Building and running a ARM system image with QEMU?

This is a great question and one I chose to dig into myself a while ago, only for me it was using MIPS/MIP64. There are a few issues which make this challenging. When booting a Linux host the Kernel ...
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7 votes

How to remove a systemd wrapper script for sysV service and use a unit file instead?

Synchronizing state of rng-tools.service with SysV service script with /lib/systemd/systemd-sysv-install. Executing: /lib/systemd/systemd-sysv-install enable rng-tools only means that systemd is “...
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6 votes
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How to interpret busybox "top" output?

VSZ (or VIRT, depending on the version of top) is the amount of memory mapped into the address space of the process. It includes pages backed by the process' executable file and shared libraries, its ...
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  • 41.1k
6 votes
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How do I forbid access to physical memory in Linux?

The Linux kernel has options to restrict what physical address ranges it will use as RAM, but that won't prevent buggy drivers or access through /dev/mem to escape those ranges. You won't gain ...
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