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Alexander Graf d273845ecb ACPI: allow longer device IDs
We create a list of ACPI "PNP" IDs which contains _HID, _CID, and CLS
entries of the respective devices. However, when making structs for
matching, we squeeze those IDs into acpi_device_id, which only has 9
bytes space to store the identifier. The subsystem actually captures the
full length of the IDs, and the modalias has the full length, but this
struct we use for matching is limited. It originally had 16 bytes, but
was changed to only have 9 in 6543becf26 ("mod/file2alias: make
modalias generation safe for cross compiling"), presumably on the theory
that it would match the ACPI spec so it didn't matter.

Unfortunately, while most people adhere to the ACPI specs, Microsoft
decided that its VM Generation Counter device [1] should only be
identifiable by _CID with a value of "VM_Gen_Counter", which is longer
than 9 characters.

To allow device drivers to match identifiers that exceed the 9 byte
limit, this simply ups the length to 16, just like it was before the
aforementioned commit. Empirical testing indicates that this
doesn't actually increase vmlinux size on 64-bit, because the ulong in
the same struct caused there to be 7 bytes of padding anyway, and when
doing a s/M/Y/g i386_defconfig build, the bzImage only increased by
0.0055%, so negligible.

This patch is a prerequisite to add support for VMGenID in Linux, the
subsequent patch in this series. It has been confirmed to also work on
the udev/modalias side in userspace.

[1] https://download.microsoft.com/download/3/1/C/31CFC307-98CA-4CA5-914C-D9772691E214/VirtualMachineGenerationID.docx

Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com>
[Jason: reworked commit message a bit, went with len=16 approach.]
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-03-12 18:00:56 -07:00
arch - Fix the ptrace regset xfpregs_set() callback to behave according to the ABI 2022-02-20 12:46:21 -08:00
block block/wbt: fix negative inflight counter when remove scsi device 2022-02-17 07:54:03 -07:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: af_alg - get rid of alg_memory_allocated 2022-02-15 14:29:04 +00:00
Documentation random: remove ifdef'd out interrupt bench 2022-02-21 21:14:00 +01:00
drivers random: add mechanism for VM forks to reinitialize crng 2022-03-12 18:00:56 -07:00
fs fs.mount_setattr.v5.17-rc4 2022-02-20 11:01:47 -08:00
include ACPI: allow longer device IDs 2022-03-12 18:00:56 -07:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel random: clear fast pool, crng, and batches in cpuhp bring up 2022-02-21 21:14:21 +01:00
lib random: remove unused tracepoints 2022-02-21 21:14:00 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: don't try to NUMA-migrate COW pages that have other uses 2022-02-17 08:57:47 -08:00
net ipv6: fix data-race in fib6_info_hw_flags_set / fib6_purge_rt 2022-02-17 09:48:24 -08:00
samples samples/seccomp: Adjust sample to also provide kill option 2022-02-10 19:09:12 -08:00
scripts kconfig: fix failing to generate auto.conf 2022-02-12 23:24:19 +09:00
security integrity-v5-17-fix 2022-02-07 09:55:14 -08:00
sound ASoC: intel: skylake: Set max DMA segment size 2022-02-17 09:39:44 +01:00
tools fs.mount_setattr.v5.17-rc4 2022-02-20 11:01:47 -08:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt Two larger x86 series: 2022-01-28 19:00:26 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Christian Brauner's email address 2022-02-01 11:21:31 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2022-02-20 11:23:48 -08:00
Makefile Linux 5.17-rc5 2022-02-20 13:07:20 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.