Chroot broken on arm64

NeddySeagoon · Posted: Thu Sep 28, 2017 10:12 am Post subject: Chroot broken on arm64

Team,

I got may arm64 install into a state where it either won't boot because it hangs when it should be making static dev nodes, or it won't start mate or xfre4 due to a missing symbol.
So I've tried to chroot in from an older install as follows.

LIsLinuxIsSogood · Veteran Joined: 13 Feb 2016 Posts: 1179

Maybe boot from sysrescueCD (assuming that you haven't already tried that?)

NeddySeagoon · Posted: Fri Sep 29, 2017 10:06 am Post subject:

LIsLinuxIsSogood,

Its arm64, not amd64. It will be a year or two before System Rescue CD supports that arch.
The system is a Raspberry Pi 3 in 64 bit mode. Its all a bit like the wild west :)

I've tried booting from an image of the broken install as it was 9 months ago. That boots but won't chroot.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

nokilli · Apprentice Joined: 25 Feb 2004 Posts: 196

You've helped so many people here including myself and so there's a natural desire to return the favor but all I got is maybe it's a permissions problem? Something you no doubt dismissed in the first few seconds of considering the problem.

Usually with chroots that where things go awry in my experience.
_________________
Today is the first day of the rest of your Gentoo installation.

NeddySeagoon · Posted: Fri Sep 29, 2017 8:16 pm Post subject:

nokilli,

All help gratefully received. I think its probably something silly that I'm doing.

This may not be related.
The system I'm trying to chroot into won't boot on its own. It stalls when it should be making static device nodes for the kernel.
If I downgrade glibc (thats a silly thing to do - don't do that at home) while portage isn't looking. It boots.
I've not tested the chroot with an older glibc.

Downgrading glibc prevents Xfce4 and/or Mate from working, so that's not an option but it does have the advantage that it boots :)

Rule One is assume nothing.
Feel free to ask anything you consider relevant.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

OK, so a couple of questions mainly for my own benefit, but who knows, they may trigger an idea.

Keep in mind that I have little more than an ethereal concept that glibc provides "core libraries."

NeddySeagoon · Posted: Sat Sep 30, 2017 9:16 am Post subject:

pjp,

My first though, was how can I determine that?
After a little pondering, I can fill the init scripts with echo commands. That should tell me what was executed last.

I did try the Interactive boot mode but I have to say "No" to services so early, that its no better than init=/bin/bash.
init=/bin/bash works as well as you would expect it to.

-- edit --

After poking about with lots of echo statements, it appears that

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Well, my perhaps overly unrealistic thought was doing something similar in either the kernel or glibc code. But I may have misremembered whether or not you did development. My thinking was that when the "create_device_node()" function was run, something in that was messed up.

vaxbrat · l33t Joined: 05 Oct 2005 Posts: 731 Location: DC Burbs

Could you be missing something in the static /dev tree that's there in the initial filesystem? That would either be the initramfs or the root one itself if you don't bother to use one and then pivot.

NeddySeagoon · Posted: Sun Oct 01, 2017 9:25 am Post subject:

pjp, vaxbrat,

Responses intermingled.

I got into this mess by doing an update. The update included glibc. After that build, I noticed sandbox errors about couldn't bind some signals.
From memory, signals 3, 10 and 15. I can do the glibc downgrade, boot and glibc upgrade if exact numbers are important.
It may even be in some of the build logs.

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Unfortunately it was well beyond me at the beginning. What seems strange is that xfce stopped working with the downgrade. And I'm guessing the downgrade was to versions on which xfce4 previously worked?

Hopefully the bug is promising. Have you tried the suggestion of disabling stack protection?
_________________
Quis separabit? Quo animo?

NeddySeagoon · Posted: Mon Oct 02, 2017 9:14 am Post subject:

Team,

Its actually several problems. I'm unravelling it a bit at a time.

Downgrading glibc to 2.24-r3 allows booting to work.

The updated broken glibc-2.25.x provides a new symbol that libbsd-0.8.6 depends on.
Downgrading glibc to 2.24-r3 and libbsd to 0.8.5 allows both Xfce4 and Mate to work.

Strictly speaking the libbsd-0.8.6.ebuild should have an RDEPEND on >=glibc-2.25
but we don't tend to do that as glibc is in the system set and just works.
Its only ~arch users and beyond that will get caught out, then only when they downgrade glibc,
which is, according the the error message, "a sure way to break your system".

I've built glibc with disabling stack protection, as per the bug but it didn't install due
to file collisions. I'll install the tarball and see what happens.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

mDup · Apprentice Joined: 14 Apr 2006 Posts: 212