| Newsgroups |
gmane.linux.lfs.book |
| Message-ID |
<[email protected]> |
This is an automated email from the git hooks/post-receive script.
git pushed a commit to branch trunk
in repository lfs.
commit 5ee35073fbe1229ed984514c6ac1496c5224e20c
Author: Xi Ruoyao <[email protected]>
AuthorDate: Wed Oct 30 20:51:59 2024 +0800
drm-panic: kernel: Explain DRM panic settings
---
chapter10/kernel.xml | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/chapter10/kernel.xml b/chapter10/kernel.xml
index 8155f735c..e078e136d 100644
--- a/chapter10/kernel.xml
+++ b/chapter10/kernel.xml
@@ -272,6 +272,71 @@
</listitem>
</varlistentry>
+ <varlistentry>
+ <term>
+ <parameter>
+ Display a user-friendly message when a kernel panic occurs
+ </parameter>
+ </term>
+ <listitem>
+ <para>This will make the kernel correctly display the message
+ in case a kernel panic happens and a running DRM driver
+ supports to do so. Without this, it would be more
+ difficult to diagnose a panic: if no DRM driver is running,
+ we'd be on the VGA console which can only hold 24 lines and
+ the relevent kernel message is often flushed away; if a DRM
+ driver is running, the display is often completely messed up
+ on panic. As of Linux-6.12, none of the dedicated drivers for
+ mainstream GPU models really supports this, but it's supported by
+ the <quote>Simple framebuffer driver</quote> which runs on the
+ VESA (or EFI) framebuffer before the dedicated GPU driver is
+ loaded. If the dedicated GPU driver is built as a module
+ (instead of a part of the kernel image) and no initramfs is
+ used, this functionality will work just fine before the root
+ file system is mounted and it's already enough for providing
+ information about most LFS configuration errors causing a
+ panic (for example, an incorrect <parameter>root=</parameter>
+ setting in <xref linkend='ch-bootable-grub'/>).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <parameter>
+ Panic screen formatter
+ </parameter>
+ </term>
+ <listitem>
+ <para>Set this <literal>kmsg</literal> to make sure the last
+ kernel messages lines are displayed when a kernel panic happens.
+ The default, <literal>user</literal>, would make the kernel show
+ only a <quote>user friendly</quote> panic message which is not
+ helpful on diagnostic. The third choice,
+ <literal>qr_code</literal>, would make the kernel to compress
+ the last kernel message lines into a QR code and display it.
+ The QR code can hold more message lines than plain text and it
+ can be decoded with an external device (like a smart phone).
+ But it requires a Rust compiler that LFS does not provide.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <parameter>
+ Mark VGA/VBE/EFI FB as generic system framebuffer
+ </parameter> and
+ <parameter>Simple framebuffer driver</parameter>
+ </term>
+ <listitem>
+ <para>These allow to use the VESA framebuffer (or the EFI
+ framebuffer if booting the LFS system via UEFI) as a DRM device.
+ The VESA framebuffer will be set up by GRUB (or the EFI
+ framebuffer will be set up by the UEFI firmware), so the DRM panic
+ handler can function before the GPU-specific DRM driver is
+ loaded.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term>
<parameter>
--
To stop receiving notification emails like this one, please contact
the administrator of this repository.
--
http://lists.linuxfromscratch.org/sympa/info/lfs-book
Unsubscribe: See the above information page