Hi Dan, On Sun, May 7, 2017 at 8:26 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Sun, May 7, 2017 at 9:20 AM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: >> On Sat, May 6, 2017 at 4:21 AM, Linux Kernel Mailing List >> <linux-kernel@xxxxxxxxxxxxxxx> wrote: >>> Web: https://git.kernel.org/torvalds/c/b0686260fecaa924d8eff2ace94bee70506bc308 >>> Commit: b0686260fecaa924d8eff2ace94bee70506bc308 >>> Parent: d8f07aee3f2fd959878bf614d4e984900018eb9e >>> Refname: refs/heads/master >>> Author: Dan Williams <dan.j.williams@xxxxxxxxx> >>> AuthorDate: Thu Jan 26 20:37:35 2017 -0800 >>> Committer: Dan Williams <dan.j.williams@xxxxxxxxx> >>> CommitDate: Thu Apr 20 11:57:52 2017 -0700 >>> >>> dax: introduce dax_direct_access() >>> >>> Replace bdev_direct_access() with dax_direct_access() that uses >>> dax_device and dax_operations instead of a block_device and >>> block_device_operations for dax. Once all consumers of the old api have >>> been converted bdev_direct_access() will be deleted. >>> >>> Given that block device partitioning decisions can cause dax page >>> alignment constraints to be violated this also introduces the >>> bdev_dax_pgoff() helper. It handles calculating a logical pgoff relative >>> to the dax_device and also checks for page alignment. >>> >>> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> >> >> This looks like a fairly innocent change... >> >>> --- >>> block/Kconfig | 1 + >>> drivers/dax/super.c | 39 +++++++++++++++++++++++++++++++++++++++ >>> fs/block_dev.c | 14 ++++++++++++++ >>> include/linux/blkdev.h | 1 + >>> include/linux/dax.h | 2 ++ >>> 5 files changed, 57 insertions(+) >>> >>> diff --git a/block/Kconfig b/block/Kconfig >>> index e9f780f815f5..93da7fc3f254 100644 >>> --- a/block/Kconfig >>> +++ b/block/Kconfig >>> @@ -6,6 +6,7 @@ menuconfig BLOCK >>> default y >>> select SBITMAP >>> select SRCU >>> + select DAX > > Whoops, yes, that should be "select DAX if FS_DAX". We don't need the > DAX core if we're never going to mount a DAX capable filesystem. Good, thanks! >> Furthermore: >> >> Maximum number of Device-DAX instances (NR_DEV_DAX) [32768] (NEW) ? >> >> There is no help available for this option. >> Symbol: NR_DEV_DAX [=32768] >> Type : integer >> Range : [256 2147483647] >> Prompt: Maximum number of Device-DAX instances >> Location: >> -> Device Drivers >> -> DAX: direct access to differentiated memory (DAX [=y]) >> Defined at drivers/dax/Kconfig:31 >> Depends on: DAX [=y] >> >> What should I answer here? >> "256" already sounds like a large number to me, "32768" sounds huge, and >> "2147483647" sounds insane? But perhaps this doesn't really mean what I >> would expect... >> >> Can you please add some help for this option? > > Will do. The number gets passed directly to the @count parameter of OK, thanks! > alloc_chrdev_region(). BTW, I saw that. But it still didn't give me a clue about a useful value. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
