Tag: archLinux

Configure static IP address on Arch Linux

I use NetworkManager to manage network on Arch Linux:

# systemctl --type=service
  UNIT                               LOAD   ACTIVE SUB     DESCRIPTION                               >
  dbus.service                       loaded active running D-Bus System Message Bus                  >
  getty@tty1.service                 loaded active running Getty on tty1                             >
  kmod-static-nodes.service          loaded active exited  Create list of static device nodes for the>
  NetworkManager.service             loaded active running Network Manager
......

So I will leverage nmcli to configure static IP address:

(1) Check current connection:

# nmcli con show
NAME                UUID                                  TYPE      DEVICE
Wired connection 1  f1014ad6-4291-3c29-9b0d-b552a0c5eb02  ethernet  enp0s3

(2) Configure IP address, gateway and DNS:

# nmcli con modify f1014ad6-4291-3c29-9b0d-b552a0c5eb02 ipv4.addresses 192.168.1.124/24
# nmcli con modify f1014ad6-4291-3c29-9b0d-b552a0c5eb02 ipv4.gateway 192.168.1.1
# nmcli con modify f1014ad6-4291-3c29-9b0d-b552a0c5eb02 ipv4.dns "8.8.8.8"
# nmcli con modify f1014ad6-4291-3c29-9b0d-b552a0c5eb02 ipv4.method manual

(3) Active connection:

# nmcli con up f1014ad6-4291-3c29-9b0d-b552a0c5eb02

It is done! BTW, the connection file can be found:

# cat /etc/NetworkManager/system-connections/Wired\ connection\ 1.nmconnection
[connection]
id=Wired connection 1
uuid=f1014ad6-4291-3c29-9b0d-b552a0c5eb02
type=ethernet
autoconnect-priority=-999
interface-name=enp0s3
......

Reference:
How to Configure Network Connection Using ‘nmcli’ Tool.

Fix “identifier “__builtin_is_constant_evaluated” is undefined” error on Arch Linux

The Arch Linux has shipped gcc 9, but the newest CUDA V10.1.168 still only supports gcc 8. So I met following error after upgrading Arch Linux:

......
/usr/include/c++/9.1.0/bits/stl_function.h(437): error: identifier "__builtin_is_constant_evaluated" is undefined
......

Unfortunately, gcc-8 package is not ready now. So I fell back to gcc-7:

SET(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} -ccbin=gcc-7"}

Although the CUDA release note claims it already supports clang 8, I indeed bumped into some compile errors when using clang 8. So using gcc-7 is a feasible work-around for me.

Update keyring first if your Arch Linux is old enough

My Arch Linux is not updated for nearly 3 months. When running pacman -Syu, it prompts following errors:

$ sudo pacman -Syu
......
error: python-dnspython: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python-dnspython-1.16.0-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: python-distlib: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python-distlib-0.2.8-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: python-pytoml: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python-pytoml-0.1.20-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: python2-distlib: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python2-distlib-0.2.8-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: python2-dnspython: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python2-dnspython-1.16.0-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: python2-pytoml: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/python2-pytoml-0.1.20-1-any.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: qbittorrent: signature from "Eli Schwartz <eschwartz@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/qbittorrent-4.1.5-1-x86_64.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]
error: failed to commit transaction (invalid or corrupted package)
Errors occurred, no packages were upgraded.
......

The solution is updating archlinux-keyring first:

$ sudo pacman -S archlinux-keyring

Then all goes well!

Forgetting “-pthread” option may give you a big surprise!

Today, I wrote a small pthread program to do some testing:

#include <pthread.h>

int main(void)
{
        pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
        pthread_cond_t cv = PTHREAD_COND_INITIALIZER;

        pthread_mutex_lock(&mutex);
        pthread_cond_wait(&cv, &mutex);
        return 0;
}

Build and test it on OpenBSD-current (version is 6.4):

# cc cv_test.c -o cv_test
# ./cv_test

The program will block there and it is my expected result. Switch to Arch Linux (kernel version is 4.18.9):

# cc cv_test.c -o cv_test
# ./cv_test
#

The program will exit immediately. I doubt it is “spurious awake” firstly, but can’t get a convincing explanation. Using ldd to check program. On OpenBSD:

# ldd cv_test
cv_test:
        Start            End              Type  Open Ref GrpRef Name
        000000d4c3a00000 000000d4c3c02000 exe   1    0   0      cv_test
        000000d6e6007000 000000d6e62f6000 rlib  0    1   0      /usr/lib/libc.so.92.5
        000000d6db100000 000000d6db100000 ld.so 0    1   0      /usr/libexec/ld.so

On Arch Linux:

# ldd cv_test
        linux-vdso.so.1 (0x00007ffde91c6000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007f3e3169b000)
        /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007f3e3187a000)

Nothing special. After seeking help on stackoverflow, the answer is I need adding -pthread option:

# cc -pthread cv_test.c -o cv_test
# ./cv_test

This time it worked perfectly. Checking linked library:

# ldd cv_test
        linux-vdso.so.1 (0x00007fff48be8000)
        libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007fa46f84c000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007fa46f688000)
        /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007fa46f888000)

Why doesn’t Linux give me a link error which prompts I need link libpthread? It seems not make sense.

First taste of MPI

Different with OpenMP which focuses on multiple threads in one process, MPI defines how multiple processes can collaborate with each other. In this post, I use Open MPI on Arch Linux to do a simple test.

The “Hello World” program is from here, build and run it on one node, not a cluster containing many nodes:

$ mpirun mpi_hello_world
Hello world from processor tesla-p100, rank 16 out of 52 processors
Hello world from processor tesla-p100, rank 34 out of 52 processors
Hello world from processor tesla-p100, rank 35 out of 52 processors
......

Check the CPU information:

$ lscpu
Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              104
On-line CPU(s) list: 0-103
Thread(s) per core:  2
Core(s) per socket:  26
Socket(s):           2
NUMA node(s):        2
......

Although there are 2 physical CPUs in the system, the mpirun only utilizes 1 CPU. Modify the program to output process ID:

......
#include <unistd.h>
......
printf("Hello world from process %d, processor %s, rank %d out of %d processors\n",
         getpid(), processor_name, world_rank, world_size);
......

This time you can make sure different processes are spawned:

$ mpirun mpi_hello_world
Hello world from process 52528, processor tesla-p100, rank 21 out of 52 processors
Hello world from process 52557, processor tesla-p100, rank 31 out of 52 processors
Hello world from process 52597, processor tesla-p100, rank 43 out of 52 processors
......

P.S., if you run mpirun as root, please add --allow-run-as-root option:

# mpirun --allow-run-as-root mpi_hello_world