x11failsafe - deprecated?

[magist3r]

I see 'x11failsafe' and 'nomodeset' in failsafe_kernel_options. By the way I can't boot my image with any of these options (X doesn't start at all). I think these options are deprecated and need to be removed. Thoughts?

[schaefi]

Let's ask the X experts

I'll drop Stefan Dirsch a note

[sndirsch]

Just verified, that YaST2 still writes /etc/X11/xorg.conf.install (the assumably working X configuration during install) during installation of our currently developed enterprise product (i.e. sle15), based on Tumbleweed. So "x11failsafe" still makes sense on regular installations (at least if you still use xdm; seems to be ignored by gdm e.g.). Of course this may not apply to image installations not using YaST for installation at all. 'nomodeset' still disables KMS support, so X falls back to fbdev X driver, which should be even more safe to use than 'modeset' X driver on top of KMS.

[sndirsch]

@magist3r I need to know, why X fails to start with these options. Could you attach /var/log/Xorg.0.log, please when using xdm as display manager?

[magist3r]

I can run X using startx command btw after login to console.
@schaefi could you provide some minimal graphical kiwi config with xdm to test it?

[magist3r]

Ok, looks like I found the root of the problem:

● display-manager.service - X Display Manager
Loaded: loaded (/usr/lib/systemd/system/display-manager.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Fri 2017-12-01 22:23:04 EST; 1min 25s ago
Process: 6293 ExecStart=/usr/lib/X11/display-manager start (code=exited, status=6)

Dec 01 22:23:03 linux display-manager[6293]: KEYTABLE: us
Dec 01 22:23:03 linux display-manager[6293]: Command: localectl set-keymap us
Dec 01 22:23:04 linux display-manager[6293]: I: Using systemd /usr/share/systemd/kbd-model-map mapping
Dec 01 22:23:04 linux display-manager[6293]: Starting service sddm
Dec 01 22:23:04 linux display-manager[6293]: The failsafe X.Org configuration /etc/X11/xorg.conf.install no longer exists.
Dec 01 22:23:04 linux display-manager[6293]: Either move it back (if still available) or copy /etc/X11/xorg.conf to
Dec 01 22:23:04 linux display-manager[6293]: /etc/X11/xorg.conf.install to use the native graphics driver instead of the
Dec 01 22:23:04 linux display-manager[6293]: failsafe graphics driver. Of course the latter option no longer can be called
Dec 01 22:23:04 linux display-manager[6293]: failsafe.
Dec 01 22:23:04 linux display-manager[6293]: ..unused

nomodeset option works as expected.

[sndirsch]

That's exactly the behaviour as designed. Bailout in failsafe mode, if no safe X configuration exists.
Check /usr/lib/X11/display-manager. Linux console looks more failsafe to me than a possibly freezing Xserver during startup.

[magist3r]

Ok. Where this file comes from? It is created during installation process?
I think that I can simply copy this file from my system (Leap 42.3) to image description to solve this issue.

[sndirsch]

Yes, the file is created during a regular YaST2 installation process, but this may not apply to your image installation. Yes, you can copy it from your Leap 42.3 system. I noticed, that the error message is no longer correct. There is no xorg.conf any longer (completely replaced by xorg.conf.d snippets). I will adjust this.

[magist3r]

Ok.
@schaefi maybe add /etc/X11/xorg.conf.install to generic image descriptions to provide graphical failsafe login? And mention it in doc?

[schaefi]

@magist3r /etc/X11/xorg.conf.install is not owned by any package and created from the YaST startup code afaik. So there is no reliable source for this file and we could only go and add a static overlay file which will probably be out of sync with what yast creates very soon.

I'm more open to delete the use of x11failsafe by kiwi and leave it up to the author of the image description to add that option in its image description when needed which also implies that a file /etc/X11/xorg.conf.install needs to be provided along with the image description.

In a suse specific documentation section it would also be possible to document the use and requirements of x11failsafe

nomodeset seems to be used by the kernel, thus I expect this to be generically valid and could stay as part of kiwi's standard failsafe boot

Thoughts ?

[sndirsch]

Correct, xorg.conf.install is being created on-the-fly by YaST2 during installation, so kiwi repackaging it won't fly. And, if it's not being used during installation, we simply cannot assume it is safe anyway! So there's no point in providing it.
IMO if we no longer can start a safe Xsession, we should no longer try to start X at all in failsafe mode. So replace "x11failsafe" with "3", i.e. start in runlevel 3 without X. This should also prevent Wayland sessions trying to be started, that may also suffer from graphics driver issues.

[sndirsch]

And yes, nomodeset definitely still makes sense, since KMS can break Linux console from the beginning, not only X/Wayland.

[magist3r]

I'm more open to delete the use of x11failsafe by kiwi and leave it up to the author of the image description to add that option in its image description when needed which also implies that a file /etc/X11/xorg.conf.install needs to be provided along with the image description.

This is the best option I think.

[sndirsch]

Then what's still left in "failsafe_kernel_options"?

[schaefi]

This is the current list:

@classmethod
    def get_failsafe_kernel_options(self):
        """
        Failsafe boot kernel options

        :return: kernel options list
        :rtype: list
        """
        return ' '.join(
            [
                'ide=nodma',
                'apm=off',
                'noresume',
                'edd=off',
                'powersaved=off',
                'nohz=off',
                'highres=off',
                'processor.max+cstate=1',
                'nomodeset',
                'x11failsafe'
            ]
        )

If we agree on the solution I would delete x11failsafe from the list

Does the rest still makes sense from your point of view ?

Keep in mind this list is rather old and has been inherited from the former kiwi version

Thanks for your feedback

[sndirsch]

Well, I disagree. I would replace "x11failsafe" with "3" (i.e. runlevel 3 without X). Reason I've given before. I guess many of the other options are meanwhile outdated/irrelevant/ignored or even should no longer been used. I suggest to ask on our internal 'research' or 'kernel' ML or external opensuse-factory list for help. Or you can try to figure out yourself by investing hours of research ...

[schaefi]

Hmm, why do you think "failsafe kernel options" == "No X11" I think that's not what a customer would expect. I think failsafe boot means "less performance but failsafe". Correct me when I'm wrong but switching off kernel modesetting still means I can have X or is that wrong ?

The setup of the runlevel is in the hand of the one who designs the image, I think forcing a runlevel would be the wrong way to go unless the other kernel options really cause that

I guess many of the other options are meanwhile outdated/irrelevant/ignored or even should no >longer been used

I'll check our official product iso and see which options are used here

[sndirsch]

Well, with no xorg.conf.install available we don't have a failsafe X configuration. So if the graphics driver is the issue, and my guess is that in most cases this is the reason to boot into failsafe, we gain exactly nothing with this failsafe kernel boot entry. Of course you can tell then the customer to add "3" in addition. OTOH with nomodeset we disable KMS and most drivers meanwhile require KMS, so we see as fallback driver either fbdev or vesa (if framebuffer has been disabled as well). And these drivers hopefully will just work.

[schaefi]

ok so failsafe in fact means no X. Thanks I'll adapt the list and also set the runlevel as you suggested

[sndirsch]

Thanks!

[schaefi]

@sndirsch could you take a short look on the pull request ? Thanks