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nelsonwcf
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PostPosted: Sun May 01, 2016 12:38 am    Post subject: udev service hanging up at boot [Solved] Reply with quote

Hi Guys,

I was trying to boot Gentoo LiveCD in my gaming laptop and it hangs during the booting process with the following message:

udev: waiting for uevents to be processed

but hang up there. I've read in another thread in this forum that this could indicate hardware issues. Is there a way for me to debug what is causing this hangup more specifically?

Thank you,
Nelson


Last edited by nelsonwcf on Fri Jun 17, 2016 3:12 pm; edited 1 time in total
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krinn
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PostPosted: Sun May 01, 2016 8:36 am    Post subject: Reply with quote

Certainly you have an hw that need a firmware, livecd found the right driver and load it, and loading the driver hang while it try to get firmware loaded.

What you could do, is boot and wait the timeout to pass, once the livecd has boot, look in dmesg for the firmware error message and on next boot, try passing modprobe.blacklist=drivername to kernel command line.

You could also use another livecd, gentoo doesn't really care to be install with its livecd or one from another distro.
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nelsonwcf
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PostPosted: Sun May 01, 2016 8:24 pm    Post subject: Reply with quote

Well, I've waited for around 30 minutes and it didn't timeout. Is it still possible to be a timeout problem?

Also, not all firmware problems were reported in the boot log (for example, the iwlwifi driver for the Intel 7260 boots but takes 5 minutes after the prompt appear to recognize the wireless card. No message was issued in the Dmesg; some kind soul of this forum explained that it would very likely be the firmware).

Any advice?
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nelsonwcf
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PostPosted: Tue May 03, 2016 2:13 am    Post subject: LiveCD - Possible way to identify defective hardware/issues: Reply with quote

Hi Guys,

After successfully installing it in my working notebook and in a BananaPi SoC, I decided to install Gentoo in my gaming notebook. As I did previously, I booted the Gentoo LiveCD in EFI mode in my notebook but during the kernel boot process, the system hangs with the following line:

udev: waiting for uevents to be processed [Ok]

From what I could understand to this point, it could mean that the kernel may be trying to load an incompatible module, the notebook may have a defective hardware or a firmware could be hanging up the system. I got the advice in a previous thread that this issue could be resolved analyzing the logs after the timeout. However, I've waited for 30 minutes and the boot process didn't move forward.

What should be my next approach to try to understand why udev is hanging my computer? I mean, is there a way to find which module, if any, is causing this?

Thank you,
Nelson

Obs.: I have a similar thread created in hardware section of the forum but I figured out that this section is more adequate to this question. However, I can't neither move nor delete the previous thread. It would be okay for any admin to move or exclude that thread at hardware section.
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PostPosted: Tue May 03, 2016 2:56 am    Post subject: Re: Gentoo LiveCD hanging up - Udev Issues: Reply with quote

nelsonwcf wrote:
[...] I've read in another thread in this forum that this could indicate hardware issues. Is there a way for me to debug what is causing this hangup more specifically?

nelsonwcf ... I would first try with another boot disk, like sysresccd (try with both supplied kernels) or some other bootdisk. You can as well install with this (sysresccd is gentoo based) or any disk that boots and provides networking.

nelsonwcf wrote:
Obs.: I have a similar thread created in hardware section of the forum but I figured out that this section is more adequate to this question. However, I can't neither move nor delete the previous thread. It would be okay for any admin to move or exclude that thread at hardware section.

Rather than start another thread you could have asked for it to me moved, anyhow, I've asked that they be merged/moved, as generally one or other post would be marked 'duplicate' (and moved to the 'Duplicate Threads' sub-forum). You might want to chime in if you'd rather the old thread was moved there.

best ... khay
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nelsonwcf
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PostPosted: Tue May 03, 2016 1:39 pm    Post subject: Reply with quote

Thank khayyam, I didn't know the process to move/merge threads. Moving the thread to install works for me.

Installing or booting linux itself may not be the problem, as I already have a working "linux-from-scratch" version installed.

The problem is that the hardware is faulty, as I'm getting many BSoDs on Windows in that laptop in many different scenarios. However, the issue is very difficult to pinpoint, even when using Memory Dumps (In fact, I have been discussing with Sager support for 9 months now and each technician I talk give me a different answer but no one provides a solution nor want to replace the hardware).

Knowing which module is causing it to hang up could give me another lead to find out what is happening with the computer. If I boot from a different distro and it works, I won't be able to pinpoint the infringing module.

One idea I just had: if I could put the LiveCD in a new partition (is this possible), do you think I could use the working linux to diagnose it? Would the udev logs be saved in the new partition?

Thank you,
Nelson
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PostPosted: Tue May 03, 2016 3:00 pm    Post subject: Reply with quote

sysrescuecd also has memtest on it. If you are having hardware problems, I'd try running memtest overnight. Also, if you have a power supply tester, test the power supply. If you don't, most BIOS's have a PC health section. Look for over- or under-voltages.

If all that checks out, look to see if your PS is adequate. Most PC's run full tilt during boot. If you can, remove an add-in video card and switch to on-board video (if there is one) to see if that's the problem. Also, on sysrescuecd, boot without X to check for video driver problems.

Windows blue screens at the drop of a hat. Amazing that billions of dollars produces such as crap OS.
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nelsonwcf
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PostPosted: Tue May 03, 2016 4:41 pm    Post subject: Reply with quote

Hi Tony,

All of the basics have been covered already and the defect is likely to be on the motherboard, which can't really be tested (a particular strong evidence is that the USB ports don't always work as expected). This problem, however, is not key issue.

The key issue is why I can't Gentoo LiveCD in my computer; me thinking that udev hanging up was caused by a hardware defect was just a suggestion early in this thread. I'd like just to know which module is causing the issue. There must be a way to load driver (or other strategy/method) like Windows Safe Mode in which you can see what drivers are being loaded. I've trying pressing I for interactive mode but it doesn't go into details.

That's what I'm struggling with.

Thank you!
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PostPosted: Tue May 03, 2016 5:21 pm    Post subject: Reply with quote

most commonly, when udev hangs with the message for waiting for uevents, it is due to it trying to find a particular firmware (hence why we suggest using a different boot cd, as the gentoo livecd may not have the needed firmware that it's looking for).

If you can load from another livecd, you can find out all the modules (and firmware) that livecd loaded.

If you are intending to install gentoo using the LiveCD, you don't need to use Gentoo's to do the installation (you can use any linux livecd). As the cd is intended so you are running a linux kernel and have a shell prompt.
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PostPosted: Tue May 03, 2016 6:11 pm    Post subject: Reply with quote

What makes you think udev is to blame? This may be the next script that runs and hangs. As already said a number of times, use some Linux CD/DVD that boots and move on.
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nelsonwcf
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PostPosted: Wed May 04, 2016 1:01 am    Post subject: Reply with quote

Buffoon wrote:
What makes you think udev is to blame? This may be the next script that runs and hangs.


Because if I press "i" during the LiveCD startup, I can select if a service should be started or not. I tried skipping all udev starts and I got the to prompt. In the prompt, if do a /etc/init.d/udev start, the computer hangs again and I can't even switch ttys anymore.

Quote:
As already said a number of times, use some Linux CD/DVD that boots and move on.


I can't move on because my objective is to find out what is causing udev to hang. I already have a linux (from scratch) manually installed in the computer so I can boot. The problem is exactly figuring out what is causing the hang-up as it could be related to the hardware issues I'm having in windows. Also, if udev hangs in the LiveCD, there will be a good probability that after Gentoo is installed and configured, I will have these issues again.

Now, if udev runs at userspace, the script shouldn't be able to hang the rest of the computer. Am I right?
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PostPosted: Wed May 04, 2016 1:06 am    Post subject: Reply with quote

Methinks when you roll your own cruft-free kernel the udev will work, too. My 2c.
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nelsonwcf
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PostPosted: Wed May 04, 2016 1:09 am    Post subject: Reply with quote

Could be, but this would still beat up the value of finding what is causing the hang-up. No matter what option I select in the kernel, starting udev shouldn't be able to hang-up the computer. That's exactly what I need to find out because it could be the same hardware that is causing the BSoD.
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Tony0945
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PostPosted: Wed May 04, 2016 1:10 am    Post subject: Reply with quote

nelsonwcf wrote:
Could be, but this would still beat up the value of finding what is causing the hang-up. No matter what option I select in the kernel, starting udev shouldn't be able to hang-up the computer. That's exactly what I need to find out because it could be the same hardware that is causing the BSoD.


Or it could be a bug in udev.
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nelsonwcf
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PostPosted: Wed May 04, 2016 1:14 am    Post subject: Reply with quote

Tony0945 wrote:
nelsonwcf wrote:
Could be, but this would still beat up the value of finding what is causing the hang-up. No matter what option I select in the kernel, starting udev shouldn't be able to hang-up the computer. That's exactly what I need to find out because it could be the same hardware that is causing the BSoD.


Or it could be a bug in udev.


Yes but it wouldn't be able to hang-up the computer because it runs in userspace.
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PostPosted: Wed May 04, 2016 1:26 am    Post subject: Reply with quote

This probably is not a real hang, it just waits.

Last edited by Buffoon on Wed May 04, 2016 1:27 am; edited 1 time in total
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The Doctor
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PostPosted: Wed May 04, 2016 1:27 am    Post subject: Reply with quote

Merged as requested, into Installing Gentoo as it fits better here.

Quote:
Installing or booting linux itself may not be the problem, as I already have a working "linux-from-scratch" version installed.
LFS is a fine install medium for gentoo if dual booting is acceptable to you. The only special package you need is chroot.

Gentoo doesn't actually need a live CD of any sort. All it needs is a Linux OS with chroot. A live CD is simply the most convenient way to get one.
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nelsonwcf
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PostPosted: Mon Jun 13, 2016 12:38 pm    Post subject: [Solved] LiveCD Hanging at udev service: Reply with quote

It took some time but I figured the problem. I've been talking to Anthony Basile, the head developer of eudev and it seems that there is a kernel issue regarding Noveau video drivers.
In my case, I can't use the Noveau driver module as it was the responsible for udev hanging. Yes, udev runs on user space but depends on system calls and these were hanging the system. I removed the noveau driver from the kernel and installed the Nvidia one directly from the website and everything started working. Since gentoo LiveCD loads all modules, including Noveau, the computer hanged.

There is also a documented issue with noveau somewhere in the gentoo forum about Nvidia drivers not working in EFI mode and it is verified by the fact that if I boot in BIOS mode, the LiveCD loads correctly.

Solution: Skip the udev load in the LiveCD to install Gentoo and don't use Noveau drivers in GPT/EFI partitions.

Best,
Nelson
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PostPosted: Mon Jun 13, 2016 2:13 pm    Post subject: Re: [Solved] LiveCD Hanging at udev service: Reply with quote

nelsonwcf wrote:
There is also a documented issue with noveau somewhere in the gentoo forum about Nvidia drivers not working in EFI mode and it is verified by the fact that if I boot in BIOS mode, the LiveCD loads correctly.
Can you elaborate with a bug number or link? I have several nvidia cards and use the nouveau driver. All my computers are BIOS only but I am considering a mobo upgrade, so I am concerned about this issue, especially since nvidia support has been dropped for my cards and the old packages that did support it are out of the tree.
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nelsonwcf
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PostPosted: Wed Jun 15, 2016 11:08 pm    Post subject: Reply with quote

I'm not sure how to track the bug number, so I'm providing the links below:

https://devtalk.nvidia.com/default/topic/827139/uefi-nvidia-vga-console-complaints-/
https://wiki.gentoo.org/wiki/NVidia/nvidia-drivers (Check first "Important" notice).

When I switched from Noveau to the proprietary Nvidia drivers, it started to work again, so I guess the new version already support it. The current version of Noveau, however, doesn't (tested on kernel 4.1.x last time).

In theory, you can always disable the framebuffer or switch to the uvesafb and it should still work so you should be fine.

Best,
Nelson
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Tony0945
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PostPosted: Thu Jun 16, 2016 1:18 am    Post subject: Reply with quote

Thanks!
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