ecb5e1aa82
In emergency situations (something has gone wrong but the system continues to operate), usually important information (such as a backtrace) is generated via printk(). This information should be pushed out to the consoles ASAP. Add per-CPU emergency nesting tracking because an emergency can arise while in an emergency situation. Add functions to mark the beginning and end of emergency sections where the urgent messages are generated. Perform direct console flushing at the emergency priority if the current CPU is in an emergency state and it is safe to do so. Note that the emergency state is not system-wide. While one CPU is in an emergency state, another CPU may attempt to print console messages at normal priority. Also note that printk() already attempts to flush consoles in the caller context for normal priority. However, follow-up changes will introduce printing kthreads, in which case the normal priority printk() calls will offload to the kthreads. Co-developed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20240820063001.36405-32-john.ogness@linutronix.de Signed-off-by: Petr Mladek <pmladek@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.