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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 22:04:36 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 22:04:36 +0300
commitb2bec7d8a42a3885d525e821d9354b6b08fd6adf (patch)
tree8198d77e5b2fb8fc645ae42662b93a575910a032 /Documentation
parent783955f03de770e94a1200b8f719975f8768e76c (diff)
parent16182ac1f02c8a5fc9753f9b8b5f3ef8c01707d8 (diff)
downloadlinux-b2bec7d8a42a3885d525e821d9354b6b08fd6adf.tar.xz
Merge tag 'printk-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek: - New "no_hash_pointers" kernel parameter causes that %p shows raw pointer values instead of hashed ones. It is intended only for debugging purposes. Misuse is prevented by a fat warning message that is inspired by trace_printk(). - Prevent a possible deadlock when flushing printk_safe buffers during panic(). - Fix performance regression caused by the lockless printk ringbuffer. It was visible with huge log buffer and long messages. - Documentation fix-up. * tag 'printk-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: lib/vsprintf: no_hash_pointers prints all addresses as unhashed kselftest: add support for skipped tests lib: use KSTM_MODULE_GLOBALS macro in kselftest drivers printk: avoid prb_first_valid_seq() where possible printk: fix deadlock when kernel panic printk: rectify kernel-doc for prb_rec_init_wr()
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 52f8233f8bb8..8b5f717b8c8c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3293,6 +3293,21 @@
in certain environments such as networked servers or
real-time systems.
+ no_hash_pointers
+ Force pointers printed to the console or buffers to be
+ unhashed. By default, when a pointer is printed via %p
+ format string, that pointer is "hashed", i.e. obscured
+ by hashing the pointer value. This is a security feature
+ that hides actual kernel addresses from unprivileged
+ users, but it also makes debugging the kernel more
+ difficult since unequal pointers can no longer be
+ compared. However, if this command-line option is
+ specified, then all normal pointers will have their true
+ value printed. Pointers printed via %pK may still be
+ hashed. This option should only be specified when
+ debugging the kernel. Please do not use on production
+ kernels.
+
nohibernate [HIBERNATION] Disable hibernation and resume.
nohz= [KNL] Boottime enable/disable dynamic ticks