detect 64-bit CPU in Ruby on Mac OS X - ruby

I'm looking to differentiate between Core Solo/Duo and Core 2 Duo processors for 64-bit support.
On a Core 2 Duo, then `sysctl hw.cpu64bit_capable` gives 1, as desired, but on a 32-bit processor, it throws an error, saying:
second level name cpu64bit_capable in hw.cpu64bit_capable is invalid
What's the best way to detect a 64-bit processor?
Thanks.

You can still use your sysctl command by looking at the command's return value.
$ irb
>> system("sysctl hw.cpu64bit_capable > /dev/null 2>&1")
=> true
On 32 bit CPU it should return false.
Alternatively, depending what you're really looking for, you can test for 64 bit EFI with ioreg, though I think your CPU could still be 64 bit with a 32 bit EFI.
On a 64 bit EFI machine, you'd get this:
$ irb
>> system("ioreg -l -p IODeviceTree | grep firmware-abi | grep -q EFI64")
=> true
On a machine lacking 64 bit EFI, you'd get false.

Related

How many cores can I use when using **make -j**?

I'm using MacBook with M1 chip (10 CPU cores with 8 P cores and 2 E cores, 24 GPU cores) and want to compile some program, I wonder how I can know the number of cores I can use to compile?
Simply, what should x be in make -jx?
You can enter:
$ make -j `sysctl -n hw.ncpu`
so the answer is :
x = `sysctl -n hw.ncpu`
where the backstick characters means a command substitution, ie the result of the command inside the backsticks.

How to make cpuset.cpu_exclusive function of cpuset work correctly

I'm trying to use the kernel's cpuset to isolate my process. To obtain this, I follow the instructions(2.1 Basic Usage) from kernel doc cpusets, however, it didn't work in my environment.
I have tried in both my centos7 server and my ubuntu16.04 work pc, but neither did work.
centos kernel version:
[root#node ~]# uname -r
3.10.0-327.el7.x86_64
ubuntu kernel version:
4.15.0-46-generic
What I have tried is as follows.
root#Latitude:/sys/fs/cgroup/cpuset# pwd
/sys/fs/cgroup/cpuset
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpus
0-3
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mems
0
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpu_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mem_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# find . -name cpuset.cpu_excl
usive | xargs cat
0
0
0
0
0
1
root#Latitude:/sys/fs/cgroup/cpuset# mkdir my_cpuset
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpus
root#Latitude:/sys/fs/cgroup/cpuset# echo 0 > my_cpuset/cpuset.mems
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpu_exclusive
bash: echo: write error: Invalid argument
root#Latitude:/sys/fs/cgroup/cpuset#
It just printed the error bash: echo: write error: Invalid argument.
Google it, however, I can't get the correct answers.
As I pasted above, before my operation, I confirmed that the cpuset root path have enabled the cpu_exclusive function and all the cpus are not been excluded by other sub-cpuset.
By using ps -o pid,psr,comm -p $PID, I can confirm that the cpus can be assigned to some process if I don't care cpu_exclusive. But I have also proved that if cpu_exclusive is not set, the same cpus can also be assigned to another processes.
I don't know if it is because some pre-setting are missed.
What I expected is "using cpuset to obtain exclusive use of cpus". Can anyboy give any clues?
Thanks very much.
i believe it is a mis-understanding of cpu_exclusive flag, as i did. Here is the doc https://www.kernel.org/doc/Documentation/cgroup-v1/cpusets.txt, quoting:
If a cpuset is cpu or mem exclusive, no other cpuset, other than
a direct ancestor or descendant, may share any of the same CPUs or
Memory Nodes.
so one possible reason you have bash: echo: write error: Invalid argument, is that you have some other cgroup cpuset enabled, and it conflicts with your operations of echo 1 > my_cpuset/cpuset.cpu_exclusive
please run find . -name cpuset.cpus | xargs cat to list all your cgroup's target cpus.
assume you have 12 cpus, if you want to set cpu_exclusive of my_cpuset, you need to carefully modify all the other cgroups to use cpus, eg. 0-7, then set cpus of my_cpuset to be 8-11. After all these cpus configurations , you can set cpu_exclusive to be 1.
But still, other process can still use cpu 8-11. Only the tasks that belongs to the other cgroups will not use cpu 8-11
for me, i had some docker container running, which prevents me from setting my cpuset cpu_exclusive
with kernel doc, i do not think it is possible to use cpus exclusively by cgroup itself. One approach (i know this approach is running on production) is that we isolate cpus, and manage the cpu affinity/cpuset by ourselves

Find process where a particular system call returns a particular error

On OS X El Capitan, my log file system.log feels with hundreds of the following lines at times
03/07/2016 11:52:17.000 kernel[0]: hfs_clonefile: cluster_read failed - 34
but there is no indication of the process where this happens. Apart from that, Disk Utility could not find any fault with the file system. But I would still like to know what is going on and it seems to me that dtrace should be perfectly suited to find out that faulty process but I am stuck. I know of the function return probe but it seems to require the PID, e.g.
dtrace -n 'pidXXXX::hfs_clonefile:return { printf("ret: %d", arg1); }'
Is there a way to tell dtrace to probe all processes? And then how would I print the process name?
You can try something like this (I don't have access to an OS X machine to test it)
#!/usr/sbin/dtrace -s
# pragma D option quiet
fbt::hfs_clonefile:return
/ args[ 1 ] != 0 /
{
printf( "\n========\nprocess: %s, pid: %d, ret value: %d\n", execname, pid, args[ 1 ] );
/* get kernel and user-space stacks */
stack( 20 );
ustack( 20 );
}
For the fbt probes, args[ 1 ] is the value returned by the function.
The dTrace script will print out the process name, pid, and return value from hfs_clonefile() whenever the return value is not zero. It also adds the kernel and user space stack traces. That should be more than enough data for you to find the source of the errors.
Assuming it works on OS X, anyway.
You can use the syscall provider rather than the pid provider to do this sort of thing. Something like:
sudo dtrace -n 'syscall::hfs_clonefile*:return /errno != 0/ { printf("ret: %d\n", errno); }'
The above command is a minor variant of what's used within the built-in DTrace-based errinfo utility. You can view /usr/bin/errinfo in any editor to see how it works.
However, there's no hfs_clonefile syscall, as least as far as DTrace is concerned, on my El Capitan (10.11.5) system:
$ sudo dtrace -l -n 'syscall::hfs*:'
ID PROVIDER MODULE FUNCTION NAME
dtrace: failed to match syscall::hfs*:: No probe matches description
Also, unfortunately the syscall provider is prevented from tracing system processes by the System Integrity Protection feature introduced with El Capitan (macOS 10.11). So, you will have to disable SIP which makes your system less secure.

Where can I find file with UUID on OSX?

On Linux I can get UUID are stored in some files on system (in example /var/lib/dbus/machine-id, /proc/sys/kernel/random/uuid, /proc/sys/kernel/random/boot_id), can I find similar files on OS X?
You can use uuidgen:
/usr/bin/uuidgen
$ uuidgen
6A786B80-8D52-4344-93D1-37C95F6C803A
Your question seems somewhat confused...
If you want to generate a unique UUID for some reason, use #ergonaut's answer:
uuidgen
70095BA9-B866-42F2-9DE4-606F54EBBA88
If you want to get a unique identifier for a particular CPU/machine, you can use the system_profiler like this:
system_profiler SPHardwareDataType
Output
Hardware:
Hardware Overview:
Model Name: iMac
Model Identifier: iMac12,2
Processor Name: Intel Core i7
Processor Speed: 3.4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 16 GB
Boot ROM Version: IM121.0047.B21
SMC Version (system): 1.72f2
Serial Number (system): DGKH80PXDHJW
Hardware UUID: 1025AC04-9F9E-5342-9EF4-206EBAE40BF6
Or, if you want to select one of those values specifically, you can use:
system_profiler SPHardwareDataType | awk '/UUID/ { print $3; }'
1025AC04-9F9E-5342-9EF4-206EBAE40BF6
Or, you can use the MAC address of your primary Ethernet interface like this:
ifconfig en0 | awk '/ether/{print $2}'
3c:07:54:76:38:cd

Getting U-boot's Version from Userspace

Does anyone know of a way to get U-boot version installed from userspace? There is the fw_printenv command that provides access to U-boot's environment variables, but not the version.
If U-boot is located in mtd0, you can get version info as follows:
root#SUPERWIFI:/proc# strings /dev/mtd0 | grep U-Boot
U-Boot 1.1.4-g1c8343c8-dirty (Feb 28 2014 - 13:56:54)
U-Boot
Now running in RAM - U-Boot at: %08lx
Just an update for this.
In our version of U-Boot we changed the code for main_loop() in main.c to this:
#ifdef CONFIG_VERSION_VARIABLE
char *oldver=getenv("ver");
if(oldver==0 ||strcmp(oldver,version_string))
{
setenv("ver", version_string); /* set version variable */
saveenv();
}
#endif /* CONFIG_VERSION_VARIABLE */
So setenv/saveenv is only called, if needed by an update.
In our firmware we added
/sbin/fw_printenv -n ver > /var/config/u-boot.ver
to make the u-boot version public available.
There's no defined way to do this. Once Linux boots, u-boot is no longer running and it's RAM is reclaimed for Linux's use. Linux doesn't even know about u-boot. Nor does it have to have been booted by u-boot.
If you really want to do this, the only way to do it is to add the u-boot version to the kernel's command line, write code to scan the u-boot image in flash for it's version, or something even nastier.
An alternative solution is to read the version directly from the u-boot binary file (can be even embedded in an image file containing other binaries as well like e.g. the first stage bootloader) with e.g. mmcblk0boot0 as partition (of device mmcblk0) the bootloader resides in:
sudo grep -a --null-data U-Boot /dev/mmcblk0boot0
Site note: Does work not only for Arch Linux but e.g. Ubuntu as well.
In my devices UBoot automatically creates a "ver" environment variable containing its version:
U-Boot > printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
bootdelay=3
bootcmd=bootm fc080000 - fc060000
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 08 2010 - 17:08:32)
Environment size: 253/131068 bytes
U-Boot >
I don't use fw_printenv, but I would imagine that this variable gets passed along as well. Maybe you already have something similar in your system?
UPDATE (5/23/2012):
I added fw_printenv to my linux image and can confirm that I do see the "ver" variable:
[root#ST600 /]# fw_printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 11 2010 - 09:43:08)
bootcmd=bootm fc080000 - fc060000
bootdelay=3
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init panic=10 mem=32m
[root#ST600 /]#
Try to read uboot version this way:
Find uboot partition, eg. for MTD device:
cat /proc/mtd
For /dev/mtd5:
cat /dev/mtd5 | hexdump -C -n 64
You can't rely on fw_printenv if you want to know u-boot version.
fw_printenv just looks for the printenv partition and dumps its data. So it's OK for normal variables, but it's not OK for the "ver" variable, which is dynamic, and whose value is initialized by u-boot when it boots. The value of this variable doesn't remain after u-boot exit, except if you manually save it to environment.
For example, on my board, if I print the "ver" variable from u-boot prompt:
U-Boot > printenv ver
ver=U-Boot 2009.11-00393-g5ca9497-dirty (Nov 26 2012 - 11:08:44)
This is the real version of u-boot, coming from u-boot itself.
Now, if I boot my board and use fw_printenv:
el#board # fw_printenv | grep ver=
ver=U-Boot 2009.11-00323-gbcc6e0e (Sep 21 2012 - 11:07:19)
As you can see, it's different. Because it happens that I have a "ver" variable defined in my environment. And it doesn't match the real u-boot version.
Of course, I could go back to u-boot, use "saveenv" to update the "ver" value in the environment. Then the two values would match. But then, I should always update the environment after changing u-boot.
So, my conclusion is that using fw_printenv to get u-boot version is definitely not a good idea.
If u-boot is residing in an MTD partition then this will work:
U_BOOT_VER=$(for part in `grep u-boot-[01] /proc/mtd | cut -f 1 -d ':'`; do strings /dev/${part} | grep "^U-Boot.*("; break; done)

Resources