On Sun, Sep 11, 2016 at 8:35 PM, Nicholas Piggin <npiggin@xxxxxxxxx> wrote: > On Sun, 11 Sep 2016 10:31:35 -0700 > Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > >> As evidenced by this bug report [1], userspace libraries are interested >> in whether a mapping is DAX mapped, i.e. no intervening page cache. >> Rather than using the ambiguous VM_MIXEDMAP flag in smaps, provide an >> explicit "is dax" indication as a new flag in the page vector populated >> by mincore. > > Can you cc linux-arch when adding new syscalls (or other such things that > need arch enablement). > > I wonder if the changelog for a new syscall should have a bit more grandeur. > Without seeing patch 2, you might not know this was a new syscall just by > reading the subject and changelog. Fair point, I'll beef up the documentation if this moves past an RFC. > mincore() defines other bits to be reserved, but I guess it probably breaks > things if you suddenly started using them. The new bits are left as zero unless an application explicitly asks for them, so an existing mincore() user shouldn't break. > It's a bit sad to introduce a new syscall for this and immediately use up > all bits that can be returned. Would it be a serious problem to return a > larger mask per page? Certainly one of the new request flags can indicate that the vector is made up of larger entries. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
