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Patch series "scripts/gdb: Fixes related to lx_per_cpu()". These patches (1) fix kgdb detection on systems featuring a single CPU and (2) update the documentation to reflect the current usage of lx_per_cpu() and update an outdated example of its usage. This patch (of 2): When requested the list of threads via qfThreadInfo, gdb_cmd_query in kernel/debug/gdbstub.c first returns "shadow" threads for CPUs followed by the actual tasks in the system. Extended qThreadExtraInfo queries yield "shadowCPU%d" as the name for the CPU core threads. This behavior is used by get_gdbserver_type() to probe for KGDB by matching the name for the thread 2 against "shadowCPU". This breaks down on single-core systems, where thread 2 is the first nonshadow thread. Request the name for thread 1 instead. As GDB assigns thread IDs in the order of their appearance, it is safe to assume shadowCPU0 at ID 1 as long as CPU0 is not hotplugged. Before: (gdb) info threads Id Target Id Frame 1 Thread 4294967294 (shadowCPU0) kgdb_breakpoint () * 2 Thread 1 (swapper/0) kgdb_breakpoint () 3 Thread 2 (kthreadd) 0x0000000000000000 in ?? () ... (gdb) p $lx_current().comm Sorry, obtaining the current CPU is not yet supported with this gdb server. After: (gdb) info threads Id Target Id Frame 1 Thread 4294967294 (shadowCPU0) kgdb_breakpoint () * 2 Thread 1 (swapper/0) kgdb_breakpoint () 3 Thread 2 (kthreadd) 0x0000000000000000 in ?? () ... (gdb) p $lx_current().comm $1 = "swapper/0\000\000\000\000\000\000" Link: https://lkml.kernel.org/r/20250503123234.2407184-1-illia@yshyn.com Link: https://lkml.kernel.org/r/20250503123234.2407184-2-illia@yshyn.com Signed-off-by: Illia Ostapyshyn <illia@yshyn.com> Cc: Alex Shi <alexs@kernel.org> Cc: Brendan Jackman <jackmanb@google.com> Cc: Dongliang Mu <dzm91@hust.edu.cn> Cc: Florian Rommel <mail@florommel.de> Cc: Hu Haowen <2023002089@link.tyut.edu.cn> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kieran Bingham <kbingham@kernel.org> Cc: Yanteng Si <si.yanteng@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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.