Zbigniew Jędrzejewski-Szmek <zbyszek@xxxxxxxxx> writes: > On Fri, Jul 12, 2024 at 01:21:41PM -0400, Neal Gompa wrote: >> On Fri, Jul 12, 2024 at 1:12 PM Zbigniew Jędrzejewski-Szmek >> <zbyszek@xxxxxxxxx> wrote: >> > >> > On Fri, Jul 12, 2024 at 05:53:25PM +0100, Aoife Moloney wrote: >> > > In order to enable DRM_PANIC, you need to disable VT_CONSOLE in the >> > > kernel >> > >> > The idea for DRM_PANIC is nice, but I worry about the impact of disabling >> > VT_CONSOLE. Plymouth is not used everywhere, e.g. what about cloud images >> > and such? Also, when debugging boot troubles, removing 'rhbg' and 'quiet' >> > are the often first steps. >> > I would expect that in these cases the user has access to a serial console to get the kernel log output. Or it's a common case to read the kernel log messages on cloud instances over VT/fbcon ? >> > I cannot actually recall the last time when I had a kernel crash >> > on any of my machines… It seems like we might be sacrificing debugability >> > for a feature which would be used very rarely. >> > >> >> Do we lose the serial console as part of this? Or is there a serial >> console "thing" somewhere still? > > I think the serial console is not affected. The kernel Kconfig says: > Correct, serial console is not affected by this change. > config VT_CONSOLE > bool "Support for console on virtual terminal" if EXPERT > depends on VT > default y > help > The system console is the device which receives all kernel messages > and warnings and which allows logins in single user mode. If you > answer Y here, a virtual terminal (the device used to interact with > a physical terminal) can be used as system console. This is the most > common mode of operations, so you should say Y here unless you want > the kernel messages be output only to a serial port (in which case > you should say Y to "Console on serial port", below). > > If you do say Y here, by default the currently visible virtual > terminal (/dev/tty0) will be used as system console. You can change > that with a kernel command line option such as "console=tty3" which > would use the third virtual terminal as system console. (Try "man > bootparam" or see the documentation of your boot loader (lilo or > loadlin) about how to pass options to the kernel at boot time.) > One clarification since it seems that there is some confusion about this Kconfig option: this is not about enabling or disabling to have VTs/fbcon but just to make the kernel output its messages on the default VT (tt0 or any other tty? specified with the console= kernel cmdline parameter. The Kconfig option to enable/disable VT is CONFIG_VT and CONFIG_VT_CONSOLE is only about the kernel sending its messages to the VT. In other words, a user should still be able to log into a VT and fbcon is still attached to an (DRM emulated) fbdev. The only difference is that the kernel messages are not going to the VT. In the panic case, the DRM panic handler will show the panic message, if a DRM driver supports it. But simpledrm already does and support for most of the desktop DRM drivers is either implemented already or will support soon. For the non-panic case, as Jocelyn mentioned in the change proposal plymouth already supports redirecting the kernel messages (reading /dev/kmsg) to the VT and for systems without plymouth, a serial console could be used instead. I hope this makes more clear what's the scope of the proposed Fedora change. -- Best regards, Javier Martinez Canillas Core Platforms Red Hat -- _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
