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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?3RIau9SrXwm+zQ8srBoZem2M31BBqdwJt0B5S+FFThnnAVZYBovErJW4Nhxu?= =?us-ascii?Q?qIVh3OcEmoLlWuy68LOxPT3/xAGnwXX68q58JxDBzRnkbspakReuvEXRNAT+?= =?us-ascii?Q?lFj+pkFHj+EAgyF/JzTk70+7XZosSqf4vyWGcNv4CyhxAV60hEKryXpTCdSk?= =?us-ascii?Q?v4llpp3ag3S8E7qV+Sfda0FWYiKggOrsYoQJP5LEN/Vw/GwH54FLy7LA2pjP?= =?us-ascii?Q?2B8Ed4MucN1BO/nywgsqO8yZc1qHNLh+0FJNFN+WMrtnM64vilAA1PDkpV+N?= =?us-ascii?Q?S3RcjGvLrFpiiGpq/OcB7foW/QxrAnHS6cIw/OQK0skUKHMPRW9nEW13/8Jb?= =?us-ascii?Q?Q4b9a3Yf+6zHIpplVT+008LS3UqNT57EBb8E2LRrvmSf9RL6uNSRhQhm62WH?= =?us-ascii?Q?OJN/vhwqqXkTXydP0oIxzwGWLPoaQXKdnRgqT5fnUf9SC9IHysqpzOMxGdtN?= =?us-ascii?Q?5m/bh7HaeE7yPUQ5/g2PkejAEWp/zSXmWUTLmEzs8qcZ9EeRuMZsJccMu+sg?= =?us-ascii?Q?6T29kQGYP4waDiODWfZC+KxUAF2Zd7fjWeuDqaHsIyj/t857FC61XsrXAV5F?= =?us-ascii?Q?IsY3jS1oqXGlZKY+g2fnxvO0siuz1kCdaIwdwXUIQ5Im82NzAAb0dPhYGj+h?= =?us-ascii?Q?8Bzx+TQGkBZIWQQs++WIAX1/KWKI2efT+upxD7fagb8G//0gZJ03eH9BS4Dc?= =?us-ascii?Q?NKA+NUTeazsh6aGZQyIqzLhcfm4P3LbNb+4TR1GIHkdrDB8dZ/+rS2Uo6vpx?= =?us-ascii?Q?5Y1SzYpWT1O8ig7OIXusT8/zhe2AoVcd5C4skDVi+Lt5kBjcxcYnXLaoCu9F?= =?us-ascii?Q?wCMjVWR0O4H0fdKd5vdcWqH88r0JEo2uBcGOkxVyxBcoEykMdz1Akcm8Lt1v?= =?us-ascii?Q?/jIBQHv/812p3KskecqUUmHtWgHaJN0PfdBZr3rlAi/OLgB5libiNX0zNbQS?= =?us-ascii?Q?AAgPWEGUk1VXaKFe05VTGJ/uCHeEfbwmbpMCXRY3376g6S3CftqOxlvSnK3h?= =?us-ascii?Q?VeSJG+yUNHWNHUKkaj8JPtCdec69jeRCEy1UttYWStl4zx1dh/GE0uV4TUD+?= =?us-ascii?Q?IdCby6ditNh5Qju084zCsPTv11LkQ0Hr+i0lxebzPmc5KZLgCaKQ2LMz2Qc5?= =?us-ascii?Q?rByXOXdxSyNg7ZEckK9a/sIt3/4dap4JoMeR4waOQ9+8mkaybeHwtSRaO1CG?= =?us-ascii?Q?pEsyMZukfMTPYaLPJvsegUh1lgHKITeV5oE2gZUYzwqt43FWtuyQPdskgOJI?= =?us-ascii?Q?xm1gZgHJCjuhON6/ywuLo3z/vgQGW3i5PJJm5p4PhEwUsN52zoCXjyDGr3Lb?= =?us-ascii?Q?Us5WgrI8KK5TLyC/wY+zXLAYM2wZiOUZJ0XAZbbZcK0m57PGY2y5693vSNRk?= =?us-ascii?Q?W02e7G+65LdGyGoJ9OuhY9gL5PllUpLh+14kQ6Lw+/Fm9IuEvvP7wDnIvFiE?= =?us-ascii?Q?K/0DmFUyjVmfCWPZmuNKi+yivH7pZlHxcmmGxf4+SCiJnNVpJMvnoF+PADgJ?= =?us-ascii?Q?yKioLnmHrv2r8Q5s+U1ohP3RD5qXTsONjk3A5xafAc1y/3/OVv85oysbc5v5?= =?us-ascii?Q?qW+RxGHA+R9jii6Na5ceiLEmcdVjdfwcL3AOn6BUC1vTtSep+X6MH2d51TCV?= =?us-ascii?Q?vlkUkgfZgf8yWJWtdHkwS8zlgkF8Q6hN7LiXYMJITzdRtoa5clHnrutKolzW?= =?us-ascii?Q?ltF7vOiYmcgn4Y0k20CkbIrH0NTuZ/Tzo2HT1vb101/VYgWuzEMsMgu/3hPR?= =?us-ascii?Q?V/mcH5UwAQ=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: feb3cfc6-9f06-4fdf-4344-08de62898cb8 X-MS-Exchange-CrossTenant-AuthSource: PH0PR12MB8800.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Feb 2026 18:33:24.6842 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: KSaviAvogVH3QaPDTdNzFgh4lym3U6lSfSukV6BLFV+ZLRAfj6LKIxV71SPtIuFRgS9RYd9upWI4SQcbZunVQA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8249 On Wed, Jan 21, 2026 at 02:57:19PM +0000, david.laight.linux@gmail.com wrote: > From: David Laight > > Some compile time checks significantly bloat the pre-processor output > (particularly when the get nested). > Since the checks aren't really needed on every compilation enable with > W=c (adds -DKBUILD_EXTRA_WARNc) so the checks can be enabled per-build. > Make W=1 imply W=c so the build-bot includes the checks. > > As well as reducing the bloat from existing checks (like those in > GENMASK() and FIELD_PREP()) it lets additional checks be added > while there are still 'false positives' without breaking normal builds. > > Signed-off-by: David Laight Honestly I don't understand this. AFAIU, you've outlined a list of compiler warnings that slow the compilation down, and you group them under 'W=c' option. What is the use case for it outside of your series. I think, a typical user would find more value in an option that enables some warnings but doesn't sacrifices performance. Can you consider flipping the 'W=c' behavior? Can you please explicitly mention warnings included in W=c vs W=1? Can you report compilation time for W=0, W=1 and W=c? What if one needs to enable fast/slow warnings from 2nd or 3rd level? Would W=2c or W=3c work in this case? What does this 'c' stands for? Thanks, Yury > --- > scripts/Makefile.warn | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/scripts/Makefile.warn b/scripts/Makefile.warn > index 68e6fafcb80c..e8a799850973 100644 > --- a/scripts/Makefile.warn > +++ b/scripts/Makefile.warn > @@ -2,8 +2,9 @@ > # ========================================================================== > # make W=... settings > # > -# There are four warning groups enabled by W=1, W=2, W=3, and W=e > -# They are independent, and can be combined like W=12 or W=123e. > +# There are five warning groups enabled by W=c, W=1, W=2, W=3, and W=e > +# They are independent, and can be combined like W=12 or W=123e, > +# except that W=1 implies W=c. > # ========================================================================== > > # Default set of warnings, always enabled > @@ -109,6 +110,13 @@ KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion) > > KBUILD_CFLAGS += -Wunused > > +# > +# W=c - Expensive compile-time checks, implied by W=1 > +# > +ifneq ($(findstring c, $(KBUILD_EXTRA_WARN))$(findstring 1, $(KBUILD_EXTRA_WARN)),) > +KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARNc > +endif > + > # > # W=1 - warnings which may be relevant and do not occur too often > # > -- > 2.39.5