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-   -   A system without udev? (https://www.linuxquestions.org/questions/linux-from-scratch-13/a-system-without-udev-4175512005/)

stf92 07-23-2014 04:59 AM
A system without udev?
 
Hi: Is it possible to create a system without udev using the LFS book? I am reading version 7.5 of the book, and it does not seem to give the choice of not using udev. The book says:
Quote:
Another key benefit of LFS is that it allows you to have more control over the system without relying on someone else's Linux implementation. With LFS, you are in the driver's seat and dictate every aspect of the system.
According to this I should be given the choice to decide whether to use udev or not. But it gives not such a choice.

wpeckham 07-23-2014 06:10 AM
no udev
 
It can be done, but not easily and the path is not obvious.
You need to regress to settings (and in some cases sources) that were common about six (guestimate from memory) years ago.

I remember the change (when udev became almost required), but I have not built a system like that myself. I hope someone can chime in with some detail.

Why do you WANT to avoid udev? When it first came out I HATED it, but over time it has solved or avoided a LOT of problems!

stf92 07-23-2014 06:20 AM
Quote:
Originally Posted by wpeckham (Post 5208277)
Why do you WANT to avoid udev? When it first came out I HATED it, but over time it has solved or avoided a LOT of problems!
I think it's unnecessary for me because I only use one hotplug device, a memory stick, and that only now and then. So, it makes the system unnecessarily complex.

ReaperX7 07-23-2014 04:55 PM
There's a chapter in the BLFS book about using mknod to create all devices as static.

http://linuxfromscratch.org/blfs/vie...s/devices.html

Be careful with it because if you mess up, it can virtually kill your system.

stf92 07-23-2014 07:07 PM
Following the instructions in your link, I'm about to do
Code:
mount --bind / /mnt
cp -a /dev/* /mnt/dev
rm /etc/rc.d/rcS.d/{S10udev,S50udev_retry}
umount /mnt
After this, it says:
Quote:
At this point, the system will use static devices upon the next reboot. Create any desired additional devices using mknod.
What is a minimal set of devices I could need?

ReaperX7 07-23-2014 08:10 PM
Depends on your system, but you should at least have the the most critical devices your system would require if udev was not around.

stf92 07-24-2014 03:59 AM
I did
Code:
mount --bind / /mnt
cp -a /dev/* /mnt/dev
rm /etc/rc.d/rc.udev
umount /mnt
and everything went OK except when I ran X it hanged!

ReaperX7 07-24-2014 12:08 PM
Did you mknod the framebuffers?

stf92 07-24-2014 04:28 PM
I didn't know X uses framebuffers. What are the devices I should create?

ReaperX7 07-24-2014 07:38 PM
Look for the fb* devices first, and any video* as well.

You may want to use udev first to see which devices it creates under load and then use mknod to recreate them.


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