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[[!tag open_issue_glibc open_issue_gnumach]]

Missing `clock_gettime(CLOCK_MONOTONIC)` (e.g. for iceweasel)

It could be a mere matter of extending the mappable clock: add it to
`mapped_time_value_t` in gnumach, handle it in `gnumach/kern/mach_clock.c`, and
make `clock_gettime` use it.

BTW, also make `gettimeofday()` use it, since it's way more efficient and some
applications assume that it is.

What about adding a nanosecond-precision clock, too?  --[[tschwinge]]

IRC, freenode, #hurd, 2011-08-26:

    < pinotree> youpi: thing is: apparently i found a simple way to have a
      monotonic clock as mmap-able device inside gnumach
    < pinotree> currently, in kern/mach_clock.c there's a variable 'time',
      which gets increased on clock interrupt, and optionally modified by
      host_set_time
    < pinotree> ()
    < pinotree> if i add a new variable next to it, only increasing it on
      interrupt but not modifying it at all otherwise, would that give me a
      monotonic clock?
    < pinotree> at least on sme basic tests i did, it seems it could work that
      way
    < youpi> yes, it should work
    < braunr> sure
    < youpi> and that's the way I was considering implementing it

IRC, freenode, #hurd, 2011-09-06:

    <pinotree> yeah, i had a draft of improved idea for also handling
      nanoseconds
    <tschwinge> pinotree: Ah, nice, I thought about nanoseconds as well.
    <tschwinge> pinotree, youpi: This memory page is all-zero by default,
      right?
    <tschwinge> Can't we then say that its last int is a version code, and if
      it is 0 (as it is now), we only have the normal mapped time field, if it
      is 1, we also have the monotonic cliock and ns precision on address 8 and
      16 (or whatever)?
    <tschwinge> In case that isn't your plan anyway.
    <youpi> it's all-zero, yes
    <tschwinge> Or, we say if a field is != 0 it is valid.
    <youpi> making the last int a version code limits the size to one page
    <youpi> I was thinking a field != 0  being valid is simpler
    <youpi> but it's probably a problem too
    <youpi> in that glibc usually caches whether interfaces are supported
    <tschwinge> Wrap-around?
    <youpi> for some clocks, it may be valid that the value is 0
    <youpi> wrap-around is another issue too
    <tschwinge> Well, then we can do the version-field thing, but put it right
      after the current time field (address 8, I think)?
    <youpi> yes
    <youpi> it's a bit ugly, but it's hidden behind the structure
    <tschwinge> It's not too bad, I think.
    <youpi> yes
    <tschwinge> And it will forever be a witness of the evolving of this
      map_time interface.  :-)