if I don't like this functionality, can I have my vt consoles back ? and please stop use the argument of the security , I don't know how write it with nice words , but saying one untested software have better security that an very old one is not fair to me , is just not a good argument to me. On Fri, 2024-07-12 at 17:53 +0100, Aoife Moloney wrote: > Wiki - https://fedoraproject.org/wiki/Changes/EnableDrmPanic > Discussion Thread - > https://discussion.fedoraproject.org/t/f42-change-proposal-enable-drm-panic-system-wide/125542 > > This is a proposed Change for Fedora Linux. > This document represents a proposed Change. As part of the Changes > process, proposals are publicly announced in order to receive > community feedback. This proposal will only be implemented if > approved > by the Fedora Engineering Steering Committee. > > == Summary == > Drm_panic is a new feature in the Linux kernel that displays a panic > screen when a kernel panic occurs. This proposal is to enable > DRM_PANIC in the Fedora kernel, to improve the kernel panic user > experience. > > > == Owner == > > * Name: [[User:jfalempe| Jocelyn Falempe]], [[User:Javierm| Javier > Martinez Canillas]] > > * Email: <jfalempe@xxxxxxxxxx>, <javierm@xxxxxxxxxx> > > > == Detailed Description == > When the linux kernel panics in Fedora 40, in most cases, the screen > just freezes. > If you're in a VT console, you'll be able to see the kernel debug > information, but that is pretty hard to understand for users that are > not kernel developers. > With this feature, they will see a message saying the computer has > crashed, and they need to reboot the computer. > Drm_panic has been introduced in kernel v6.10, but is still under > active development. > > In order to enable DRM_PANIC, you need to disable VT_CONSOLE in the > kernel, this is to prevent a race condition, that if you are in a VT > console when the panic occurs, both fbcon and drm_panic will write to > the framebuffer at the same time, leading to corrupted output. > https://patchwork.freedesktop.org/series/134831/ > The drawback is that tty0 won't show the kernel kmsg, and it can be > harder to debug boot issues. But plymouth already takes care of this, > and can display the boot kmsg when no VT console is present. > https://gitlab.freedesktop.org/plymouth/plymouth/-/merge_requests/224 > And the user experience would be better, because plymouth has better > font and color support than fbcon. > > Supported drivers are simpledrm, mgag200, ast, (and imx, tidss, on > aarch64). I'm working on nouveau support, and I hope i915 and amdgpu > will add support too. > If the driver is not supported, you won't see the panic screen, but > it > won't be worse than what you have today. > > Drm panic provides different panic screens. The default is "user" > which will display a simple friendly message telling the user to > reboot the computer. But for kernel developers, you can also set it > to > "kmsg", to see the last kmsg lines (so this is equivalent to the > current fbcon). You can select the panic screen in Kconfig, or as a > module parameter (drm.panic_screen=user) or at runtime with "echo -n > kmsg > /sys/module/drm/parameters/panic_screen" > > I've also made a proof of concept to add a panic screen with a QR > code > with debugging information, which will make it easier for users to > report kernel panic in Fedora. An example can be seen here: > https://github.com/kdj0c/panic_report/issues/1 > > == Feedback == > > > == Benefit to Fedora == > This change will improve the user experience when a kernel panic > occurs. > > It's also a first step to switch to userspace console, and being able > to disable CONFIG_VT in the kernel. > VT and fbcon are legacy part of the kernel, that would reduce > maintenance burden if we can disable them, and > It will also reduce CVE impact, as userspace vulnerabilities are > usually less critical. > > == Scope == > * Proposal owners: > > Write documentation on how-to debug boot issues without VT_CONSOLE. > Maybe also change the systemd log configuration, so that it default > to > writing the log to the console. > > * Other developers: > > * Release engineering: [https://pagure.io/releng/issues #Releng issue > number > > I'm unsure if it has impact on the installer. > > * Policies and guidelines: N/A (not needed for this Change) > > * Trademark approval: N/A (not needed for this Change) > > * Alignment with the Fedora Strategy: > I think it perfectly fit the "Fedora is for everyone" goal, as the > current kernel panic (either UI freeze or kmsg output in VT) is not > user-friendly. > > == Upgrade/compatibility impact == > Enabling DRM_PANIC should be transparent to user, but disabling > VT_CONSOLE may have a visible impact. > Fortunately since Fedora 40, plymouth is able to display the kmsg > messages. > > For non-graphical boot, you can use systemd.log_target=console > systemd.log_level=info and remove rhgb and quiet to see the kernel > boot message. > > But this needs to be documented, and communicated, so that users that > debug boot issues, know about this change. > > > > == Early Testing (Optional) == > Do you require 'QA Blueprint' support? Y/N > > == How To Test == > Currently the easiest way to test, is to use the simpledrm driver, as > it can run on all hardware. So first blacklist your driver (i915, > amdgpu or nouveau), and then boot and check that you're using > simpledrm. > then you can trigger a kernel panic with: > echo c > /proc/sysrq-trigger > > As it will crash your machine, it's also possible to do this in a VM > (so disabling virtio-gpu, or vmwgfx) > > Also to check that you can still see the kernel messages at boot, in > the grub menu, remove the "quiet" kernel command argument, and you > should still see the kernel boot messages on the plymouth screen. > > > == User Experience == > With DRM panic, users will be notified that their computer crashed, > instead of it being unresponsive. > > With v6.10, it's only for a few GPU drivers (simpledrm, mgag200, > ast), > but with simpledrm, it will already catch some common kernel panic > cases, like root filesystem not found, or ramdisk corruption. > (simpledrm is used at boot, and is later replaced with > i915/amdgpu/nouveau ...) > > It also prepares for future drm panic improvements, like having a > kmsg > panic screen, (should be available in v6.11) or also have better > debugging information, using QR code. A test sample is shown at > https://github.com/kdj0c/panic_report/issues/1 > > == Dependencies == > The main dependency, is to have a kernel v6.10 or later. > To still see the kernel boot messages, there is also a dependency on > plymouth and systemd, but the versions in F40 are already good. > > > == Contingency Plan == > * Contingency mechanism: Revert the kernel configuration changes. > * Contingency deadline: N/A (not a System Wide Change) > * Blocks release? N/A > > > == Documentation == > Kernel Kconfig for DRM_PANIC: > https://elixir.bootlin.com/linux/v6.10-rc7/source/drivers/gpu/drm/Kconfig#L107 > > == Release Notes == > > -- > Aoife Moloney > > Fedora Operations Architect > > Fedora Project > > Matrix: @amoloney:fedora.im > > IRC: amoloney > -- Sérgio M. 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