x86_64
change reported architecture in new program environment and set personality flags
Synopsis
setarch
arch [options] [program
[arguments]]
arch [options] [program
[arguments]]
add an example, a script, a trick and tips
examples
setarch ppc32 rpmbuild --target=ppc --rebuild foo.src.rpm
setarch ppc32 -v -vL3 rpmbuild --target=ppc --rebuild
bar.src.rpm
setarch ppc32 --32bit rpmbuild --target=ppc --rebuild foo.src.rpm
source
Should I choose 32 or 64 bit for Linux?
To use all 8 GB naturally you should install 64-bit version.
source
How to run a minimal Linux inside a running 64-bit Windows 7
I would go for the Xming + ssh -X solution.
1) I’m not sure - but you could run your Virtual Mashine in
headless mode and launch applications through SSH. That would be
pretty non-intrusive,
2) I would.
3) If its a minimal distro you should be fine with a couple of GB
of space for the root filesystem / and around 200mb RAM.
4) Yes
source
How to tell if linux process is 64bit
You can use file to get that information:
For example:
chris@obsidian:~$ file /usr/bin/perl
/usr/bin/perl: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), for GNU/Linux 2.6.8, dynamically linked (uses shared libs), stripped
or read from /proc/
chris@obsidian:~$ file -L /proc/[PID]/exe
/proc/[PID]/exe: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for GNU/Linux 2.6.8, dynamically linked (uses shared libs), stripped
This will tell you if it is 64 or 32-bit.
source
How to reinstall GRUB2 EFI?
-
Boot your computer with a live-usb/CD in UEFI mode.
I had two boot options <flash_drive> and
UEFI: <flash_drive>, the second is needed
to expose the efi variables in
/sys/firmware/efi/ so that
efibootmgr don't fail later on. Booting with the
first option gives me the following error:
Fatal: Couldn't open either sysfs or procfs directories for accessing EFI variables.
Try 'modprobe efivars' as root.
modprobe efivars did'nt work for me.
-
chroot into the broken system (similar to the ubuntu grub2
help but with efi specificities):
sudo mount /dev/sda2 /mnt #sda2 is my root partition
sudo mount /dev/sda1 /mnt/boot/efi #sda1 is my efi partition
for i in /dev /dev/pts /proc /sys; do sudo mount -B $i /mnt$i; done
sudo cp /etc/resolv.conf /mnt/etc/ #makes the network available after chrooting
modprobe efivars # make sure this is loaded
sudo chroot /mnt
-
Depending on your linux distribution, you now do different
things.
-
For Ubuntu/Debian:
apt-get install --reinstall grub-efi-amd64
or alternatively:
apt-get install --reinstall grub-efi
update-grub
should the above give you a grub, but not a bootable one
-
For Fedora (up to 16, may work for
others):
yum reinstall grub-efi
In the following command, you have to replace sdX with
the device which has the EFI partition you want to boot
from. In --part Y you have to replace the
Y with the number of the EFI partition (as
in /dev/sdXY).
efibootmgr -c --disk /dev/sdX --part Y
efibootmgr -v # verify a new record called Linux is there
-
Now type Ctrl+D to exit chroot, unmount
everything and reboot:
for i in /sys /proc /dev/pts /dev; do sudo umount /mnt$i; done
sudo umount /mnt/boot/efi #please do this. corrupted efi partitions are not nice
sudo umount /mnt
sudo reboot
You may need to adapt this to your needs (different partition
table, separate /boot partition, etc.) and it may not be the only
option but this worked just fine for me.
A suitable live-system for fixing things is grml. There is also an extensive guide on how
to setup a bootable USB device, of which the Mac section is the
most useful actually (just create FAT32 partition, copy the
files, reboot, done).
source
Bare-metal virtualisation for the desktop
VirtualBox appears to be one of the best virtualisation tools.
Combined with Linux + Virtualisation features on chip its great.
I'm not sure what you mean by "bare metal", but you can't run
things that close, there has to be some visualization ( even if
it is a kernel hyper visor )
http://www.virtualbox.org/
It has this cool trick it does where, when using its own video
drivers in windows, can mix windows apps into your linux desktop
with a fancy compositing trick. ( effectively, the windows
desktop becomes transparent and the app drops its borders and
does other fancy reporting tricks ) and it becomes like running
X11 on Windows ( its creepy, really )
source
Ubuntu 64-bit vs 32-bit
Why not try both and decide for yourself? You can always backup
your homedir and migrate it to the version you intend to keep.
I don't know if it's the placebo effect or something else, but I
seem to think that 64-bit feels faster on the same hardware.
source
How do I know if my linux kernel is running in 32bit or 64bit?
uname -a
will tell you the kernel - the end bit tells you the
architecture.
Two examples:
My mac:
Darwin Mac.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386 i386
My Dreamhost hosting:
Linux ecco 2.6.24.5-serf-xeon-c6.1-grsec #1 SMP Tue Oct 7 06:18:04 PDT 2008 x86_64 GNU/Linux
i386 = 32 bit
x86_64 = 64 bit
source
Linux command to return number of bits (32 or 64)?
You can use uname -a and look for
x86_64 to see if you are running 64-bit. Anything
else (As far as I know) and you are running 32-bit or you are on
non-PC hardware such as alpha, sparc,
or ppc64.
source
Install 64-bit Ubuntu or 32-bit?
Plus sides:
- It will be slightly faster. While 64bit vs 32bit apps don't
make a huge performance difference, developers can make
assumptions about speed-related features being present in 64-bit
processors that they can't with 32bit apps.
- You can use all 4GB of RAM, as opposed to roughly 3.2GB.
(There are ways around this for 32bit systems, but it's not
simple)
Negative sides:
- While nowadays you won't find many apps that just don't work
on 64bit, there are some (Adobe Air comes to mind), that do
require more effort to install.
source
Getting a GPU Bitcoin miner for Linux 64bit
In my experience, Linux is far better supported by the Bitcoin
community than Windows is. The same goes for ATI vs. Nvidia; ATI
cards are far better at doing the calculations required for
mining bitcoins, so all the serious miners use them. 32 vs. 64
bit should also be a non-issue; just pick the 64-bit version of
the AMD Stream SDK instead of the 32-bit version.
Here's a guide for setting up the Phoenix and
poclbm miners on Ubuntu 11.04. Setup should be roughly similar on
other distributions.
description
setarch
This utility currently only affects the output of uname -m.
For example, on an AMD64 system, running ’setarch i386
program’ will cause ’program’ to see
i686 (or other relevant arch) instead of
x86_64 as machine type. It also allows to set various
personality options. The default program is
/bin/sh.
options
-v,
--verbose
Be verbose.
-h,
--help
Display help (it is also
displayed when setarch takes no arguments).
--uname-2.6
Causes the program to see a
kernel version number beginning with 2.6.
-3,
--3gb
Specifies that processes should
use a maximum of 3GB of address space on systems where it is
supported (ADDR_LIMIT_3GB).
-B,
--32bit
Turns on ADDR_LIMIT_32BIT.
-F,
--fdpic-funcptrs
Userspace function pointers
point to descriptors (turns on FDPIC_FUNCPTRS).
-I,
--short-inode
Turns on SHORT_INODE.
-L,
--addr-compat-layout
Changes the way virtual memory
is allocated (turns on the ADDR_COMPAT_LAYOUT).
-R,
--addr-no-randomize
Disables randomization of the
virtual address space (turns on ADDR_NO_RANDOMIZE).
-S,
--whole-seconds
Turns on WHOLE_SECONDS.
-T,
--sticky-timeouts
Turns on STICKY_TIMEOUTS.
-X
--read-implies-exec
Turns on READ_IMPLIES_EXEC.
-Z,
mmap-page-zero
Turns on MMAP_PAGE_ZERO.
availability
The setarch command is part of the util-linux package and is
available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
author
Elliot Lee
<sopwith[:at:]redhat[:dot:]com>
Jindrich Novy <jnovy[:at:]redhat[:dot:]com>