Thomas Gleixner 3d41009425 x86/cpu: Provide a sane leaf 0xb/0x1f parser
detect_extended_topology() along with it's early() variant is a classic
example for duct tape engineering:

  - It evaluates an array of subleafs with a boatload of local variables
    for the relevant topology levels instead of using an array to save the
    enumerated information and propagate it to the right level

  - It has no boundary checks for subleafs

  - It prevents updating the die_id with a crude workaround instead of
    checking for leaf 0xb which does not provide die information.

  - It's broken vs. the number of dies evaluation as it uses:

      num_processors[DIE_LEVEL] / num_processors[CORE_LEVEL]

    which "works" only correctly if there is none of the intermediate
    topology levels (MODULE/TILE) enumerated.

There is zero value in trying to "fix" that code as the only proper fix is
to rewrite it from scratch.

Implement a sane parser with proper code documentation, which will be used
for the consolidated topology evaluation in the next step.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20240212153624.830571770@linutronix.de
2024-02-15 22:07:37 +01:00
2023-12-20 19:26:31 -05:00
2024-02-07 21:20:36 -08:00
2022-09-28 09:02:20 +02:00
…
…
2024-02-11 12:18:13 -08:00
…

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 Restructured Text 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.
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