bootlogd and CONFIG_LEGACY_PTYS=y

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figueroa · Post by **figueroa** » Mon Sep 13, 2021 4:32 am

Sometime between August 12, date of last good /var/log/boot, and now, bootlogd stopped working. I don't boot very often, usually just for kernel upgrades. I usually do watch the screen during boot to catch any errors, but I may have missed this on or about August 30 when I upgraded to the current kernel.

Error on boot was:

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bootlogd: cannot allocate psuedotty:
No such file or directory

I searched for that with duckduckgo and top entry was a nine year old solution: https://meta-freescale.yoctoproject.nar ... pseudo-tty

I'm running gentoo-sources 5.4.143 and have never configured CONFIG_LEGACY_PTYS=y in kernels going back to May versions of 4.9.240 and 4.19.160 and a few more recent 5.4~ also. However, setting that, recompiling, installing and rebooting led to a solution for me too.

I have a routine that includes makeoldconfig so my kernels are pretty consistent. Anyway, if bootlogd isn't working for you, maybe this solution will work for you too. I'm happy.

Comments welcomed and even encouraged.

eccerr0r · Post by **eccerr0r** » Mon Sep 13, 2021 6:19 am

does it work on the old kernels (saved it before recompiling) or was it some other system change?

CONFIG_LEGACY_PTYS is kind of ancient, don't think it should be necessary to use it anymore, perhaps something screwed up with udev? Would have thought that ptmx isn't working properly or /dev/pts isn't mounted early enough?

Goverp · Post by **Goverp** » Mon Sep 13, 2021 7:27 am

Nope. I've a working bootlogd, and CONFIG_LEGACY_PTYS is unset - just checked!

figueroa · Post by **figueroa** » Mon Sep 13, 2021 3:21 pm

I did have an eudev-3.2.10-r1 rebuild on August 16, and and upgrade to libgudev-234-r on September 9. I do know that setting CONFIG_LEGACY_PTYS caused bootlogd to work again, even though it being unset is clearly not what caused the problem.

I don't know what tail to chase. Any troubleshooting ideas would be helpful to me. Until then, I will do some trial and error, booting from an older kernel, 5.4.134, and then maybe migrate this machine to pure udev, and check and re-check results.

eccerr0r · Post by **eccerr0r** » Mon Sep 13, 2021 3:36 pm

You may well go to systemd-udev since it's suspect and probably should switch over anyway though I think it shouldn't be the problem now.

Key things is to make sure your /dev/pts is mounted before bootlogd starts. devfs in openrc should be started in sysinit, just need to make sure you run bootlogd after devfs is started.

Hope it's not because bootlogd doesn't have a dependency for devfs and it was just so happen to run before due to random luck, or perhaps it simply works better when it's in the boot runlevel instead of sysinit?

figueroa · Post by **figueroa** » Mon Sep 13, 2021 3:47 pm

Booting earlier kernels not containing CONFIG_LEGACY_PTYS didn't pan out. grep devfs /etc/init.d/bootlogd returns nothing. I think bootlogd should have a file in /etc/conf.d/ but it does not.

eccerr0r · Post by **eccerr0r** » Mon Sep 13, 2021 4:15 pm

try /etc/conf.d/bootlogd :

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rc_need="devfs"

?

Not sure if this would be sufficient.

Else starting it in the 'boot' runlevel would be guaranteed to work.

figueroa · Post by **figueroa** » Mon Sep 13, 2021 4:30 pm

Thanks eccerr0r, that's a few tools to try over the next couple of days. Will report back here.

Leonardo.b · Post by **Leonardo.b** » Mon Sep 13, 2021 11:16 pm

bootlogd can be set in inittab, so it catches earlier output.

man bootlogd says it requires pty.
A bit terse, it's not clear to me what it means.

figueroa · Post by **figueroa** » Mon Sep 13, 2021 11:38 pm

Leonardo.b wrote:bootlogd can be set in inittab, so it catches earlier output.
...

Curious what you mean by that? Can you make an example?

eccerr0r · Post by **eccerr0r** » Tue Sep 14, 2021 1:16 am

Leonardo.b wrote:bootlogd can be set in inittab, so it catches earlier output.

man bootlogd says it requires pty.
A bit terse, it's not clear to me what it means.

As said, it can only be pushed up earlier in the flow so far, unless you're using CONFIG_LEGACY_PTYS. Without it, /dev/pts needs to be mounted before it can be started and pushing it later will allow it to reliably start.

figueroa · Post by **figueroa** » Tue Sep 14, 2021 2:12 am

eccerr0r wrote:try /etc/conf.d/bootlogd :
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rc_need="devfs"
...

That worked.

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$ cat /etc/conf.d/bootlogd
# Config file for /etc/init.d/bootlogd suggested by eccerr0r on Gentoo Forums at https://forums.gentoo.org/viewtopic-p-8657398.html
rc_need="devfs"

Haven't discerned why it suddenly stopped. Mystery remains, but your rc_need="devfs" solution is golden.

Leonardo.b · Post by **Leonardo.b** » Wed Sep 15, 2021 12:31 am

figueroa wrote:Curious what you mean by that? Can you make an example?

eccer0r's solution is simpler and more reliable.

figueroa · Post by **figueroa** » Thu Apr 14, 2022 4:34 am

Following up on this topic. In an update to sysvinit (don't know which version), all of /etc/conf.d/bootlogd was commented out, bootlogd continued to work. I subsequently unset CONFIG_LEGACY_PTYS in the kernel (running gentoo-sources-5.10.109 currently).

I have the following in /etc/logrotate.d/bootlogd:

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/var/log/boot {
        missingok
        notifempty
}

which I find convenient.

For the most part, in spite of the manual (man bootlogd), bootlogd continues to be mysterious, but it is working here.

C5ace · Post by **C5ace** » Fri Jan 30, 2026 10:13 pm

To log the boot process to the end of poweroff view /var/log/boot~.

/etc/conf.d/bootlogd:

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BOOTLOGD_ARGS="-c -r -l /var/log/boot"

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rc-update add bootlogd sysinit

To test:
1.) delete /var/log/boot
2.) reboot the PC
3.) view current boot log /var/log/boot
4.) reboot the PC
5.) view current (new) boot log /var/log/boot
6.) view previous boot log /var/log/boot~