GRUB
- Mae18
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16 Jan 2023 16:16 #262138
by Mae18
GRUB was created by Mae18
Could someone please give us a bit of advice - we have just started to use Linuxcnc and in the process of watching a few videos, in the video we are told we have to access the GRUB by going into the terminal emulator and typing in Sudo Mousepad we then get a pop up box with untitled 1 - mousepad from here we are told to go to File - Open - file system - etc- Grub, our problem is that there is no GRUB just GRUB D, we are using Debian 10 with linuxcnc has anyone got any idea we’re the GRIB file is located
Thanks in advance
Thanks in advance
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- andypugh
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16 Jan 2023 23:59 #262197
by andypugh
Replied by andypugh on topic GRUB
I think that you are probably watching very old videos.
Check the dates on any videos to be sure that what it being shown it relevant to the current LinuxCNC and Debian versions.
You are specifically advised not to hand-edit the grub file now, but instead you edit a secondary file (/etc/default/grub) and then run "sudo update-grub"
linuxhint.com/change-grub-boot-order-debian-linux/
As an example tutorial.
Check the dates on any videos to be sure that what it being shown it relevant to the current LinuxCNC and Debian versions.
You are specifically advised not to hand-edit the grub file now, but instead you edit a secondary file (/etc/default/grub) and then run "sudo update-grub"
linuxhint.com/change-grub-boot-order-debian-linux/
As an example tutorial.
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- Mae18
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17 Jan 2023 17:45 #262256
by Mae18
Replied by Mae18 on topic GRUB
Thank you, yes someone on the FB group said exactly the same. We are a little confused as the video was showing you how to get your latency test numbers down by separating the cores. Our tests are quite high but on the FB group they said they would be ok if we kept the pulse rate down and use 8 micro steps, so my question is do we need to even separate the core or can we leave it alone? Is there another way of reducing the numbers?
We only have Linux cnc on this pc and it’s not dual booted. Our readings are max jitter servo thread is 73733 and the max jitter base thread is 1000376
We are using a Dell Optiplex 755
If we do need to do the etc/default/grub can you point us in the general direction with code, the video said “quiet, isolcpus=1”
Many thanks for your help it’s much appreciated
We only have Linux cnc on this pc and it’s not dual booted. Our readings are max jitter servo thread is 73733 and the max jitter base thread is 1000376
We are using a Dell Optiplex 755
If we do need to do the etc/default/grub can you point us in the general direction with code, the video said “quiet, isolcpus=1”
Many thanks for your help it’s much appreciated
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- andypugh
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17 Jan 2023 23:10 #262282
by andypugh
Replied by andypugh on topic GRUB
Here is the contents of my /etc/default/grub file
The important line is GRUB_CMDLINE_LINUX_DEFAULT which has the isolcpus request.
Edit your own file to also have that, then run "sudo update-grub" and reboot.
By the way, something very difficult to find out anywhere, that GRUB_DEFAULT="4>2" is the syntax to choose the second kernel in the 4th sub-menu. My dev PC multi-boots into a whole range of possible OSes.
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'
GRUB_DEFAULT="4>2"
GRUB_TIMEOUT="5"
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash processor.max_cstate=1 idle=poll isolcpus=1"
GRUB_CMDLINE_LINUX=""
# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"
# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"
# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE="640x480"
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID="true"
# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"
# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"The important line is GRUB_CMDLINE_LINUX_DEFAULT which has the isolcpus request.
Edit your own file to also have that, then run "sudo update-grub" and reboot.
By the way, something very difficult to find out anywhere, that GRUB_DEFAULT="4>2" is the syntax to choose the second kernel in the 4th sub-menu. My dev PC multi-boots into a whole range of possible OSes.
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