On Sun, Jan 17, 2021 at 08:49:51PM -0500, Sasha Levin wrote: > SUBLEVEL only has 8 bits of space, which means that we'll overflow it > once it reaches 256. > > Few of the stable branches will imminently overflow SUBLEVEL while > there's no risk of overflowing VERSION. > > Thus, give SUBLEVEL 8 more bits which will be stolen from VERSION, this > should create a better balance between the different version numbers we > use. > > The downside here is that Linus will have 8 bits less to play with, but > given our current release cadence (~10 weeks), the number of Linus's > fingers & toes (20), and the current VERSION (5) we can calculate that > VERSION will overflow in just over 1,000 years, so I'm kicking this can > down the road. > > Cc: stable@xxxxxxxxxx > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > Makefile | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index 9e73f82e0d863..dc2bad7a440d8 100644 > --- a/Makefile > +++ b/Makefile > @@ -1252,8 +1252,8 @@ endef > > define filechk_version.h > echo \#define LINUX_VERSION_CODE $(shell \ > - expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \ > - echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))' > + expr $(VERSION) \* 16777216 + 0$(PATCHLEVEL) \* 65536 + 0$(SUBLEVEL)); \ > + echo '#define KERNEL_VERSION(a,b,c) (((a) << 24) + ((b) << 16) + (c))' As much as I agree, this will break in-tree users of LINUX_VERSION_CODE that try to suck out the version/patchlevel number of the kernel release into their own fields. Things like USB host controller strings, v4l ioctl reports, scsi driver ioctls, and other places do fun bit-movements to try to unreverse this bit packing. So how about we just provide a "real" version/subversion/revision #define as well, and clean up all in-kernel users, so we can get this to work, and we can change it in the future more easily. thanks, greg k-h
