Date: Tue, 21 Apr 2026 22:27:12 +0000 From: Jean-=?utf-8?Q?S=C3=A9bast?==?utf-8?Q?ien P=C3=A9?=dron <dumbbell@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: ae1f6954e2c8 - main - linuxkpi: Define `MINORBITS` Message-ID: <69e7f9c0.36bda.6e7d1768@gitrepo.freebsd.org>
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The branch main has been updated by dumbbell: URL: https://cgit.FreeBSD.org/src/commit/?id=ae1f6954e2c82ad7f1d8b80155a921b908d51756 commit ae1f6954e2c82ad7f1d8b80155a921b908d51756 Author: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> AuthorDate: 2026-04-13 21:47:22 +0000 Commit: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> CommitDate: 2026-04-21 22:18:25 +0000 linuxkpi: Define `MINORBITS` We can't really define a proper value for this constant because minor and major are encoded in a complex way on FreeBSD which cannot be represented with a simple shift. The DRM generic code started to use it in Linux 6.12. In this context, `MINORBITS` is used to define an upper limit passed to `xa_alloc()`. Therefore it is not used to encode or decode minors. It is used as an arbitrary value. Therefore, we define the constant to 20, like on Linux. Reviewed by: bz Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D56447 --- sys/compat/linuxkpi/common/include/linux/kdev_t.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/sys/compat/linuxkpi/common/include/linux/kdev_t.h b/sys/compat/linuxkpi/common/include/linux/kdev_t.h index 988dd771254a..964b7078e7f5 100644 --- a/sys/compat/linuxkpi/common/include/linux/kdev_t.h +++ b/sys/compat/linuxkpi/common/include/linux/kdev_t.h @@ -31,6 +31,21 @@ #include <sys/types.h> +/* + * The encoding of major/minor on FreeBSD is complex to take into account the + * compatibility with 16-bit dev_t (see <sys/types.h>). It is not possible to + * use a simple shift and thus, we can't have a proper definition of + * `MINORBITS`. + * + * At the time this is added to linuxkpi, this is used by the DRM generic code + * as the upper limit to allocate an ID using an xarray. It is not used to + * decode a minor, therefore any arbitrary value here is fine in this context. + * + * On Linux, the value is set to 20. Because of the above, we reuse this value, + * even so it does not correspond to the actual minor encoding on FreeBSD. + */ +#define MINORBITS 20 + #define MAJOR(dev) major(dev) #define MINOR(dev) minor(dev) #define MKDEV(ma, mi) makedev(ma, mi)home | help
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