Messages in this thread | | | Date | Thu, 10 Apr 2008 08:48:50 +0200 | From | Cedric Le Goater <> | Subject | Re: [PATCH 0/3] clone64() and unshare64() system calls |
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H. Peter Anvin wrote: > sukadev@us.ibm.com wrote: >> This is a resend of the patch set Cedric had sent earlier. I ported >> the patch set to 2.6.25-rc8-mm1 and tested on x86 and x86_64. >> --- >> >> We have run out of the 32 bits in clone_flags ! >> >> This patchset introduces 2 new system calls which support 64bit >> clone-flags. >> >> long sys_clone64(unsigned long flags_high, unsigned long flags_low, >> unsigned long newsp); >> >> long sys_unshare64(unsigned long flags_high, unsigned long >> flags_low); >> >> The current version of clone64() does not support CLONE_PARENT_SETTID >> and CLONE_CHILD_CLEARTID because we would exceed the 6 registers limit >> of some arches. It's possible to get around this limitation but we >> might not >> need it as we already have clone() >> > > I really dislike this interface. > > If you're going to make it a 64-bit pass it in as a 64-bit number, > instead of breaking it into two numbers. Better yet, IMO, would be to > pass a pointer to a structure like: > > struct shared { > unsigned long nwords; > unsigned long flags[]; > }; > > ... which can be expanded indefinitely.
ok.
What about the copy_from_user() overhead ? is this something we care about for a clone like syscall ?
If not, this would certainly make our life simpler to extend clone flags. I'm ready to implement anything if someone would just tell me in which direction.
Thanks !
C.
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