Re: [Xen-devel] [PATCH] don't use mlock() with Solaris tools

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

On Oct 22, 2006, at 2:16 PM, Keir Fraser wrote:

> On 22/10/06 7:02 pm, "John Levon" <levon@xxxxxxxxxxxxxxxxx> wrote:
>
> > > # HG changeset patch
> > > # User john.levon@xxxxxxx
> > > # Date 1161315500 25200
> > > # Node ID ad404ee927926b8cc4a6498b180e78f0939eb2eb
> > > # Parent  3685871c6f7930c7d35baea7cee4f51d00415796
> > > on solaris: mlock requires a page aligned address and mlock  
> > > doesn't ensure
> > > the pages won't minor page fault; so don't use it on solaris.
> > This isn't in unstable yet; I don't know if it was missed or if  
> > there's
> > some better way we could do this?
> >
> > thanks,
> > john
> Don't worry, it's in my to-apply list. I don't do FIFO. :-)
Hey, hang on a minute.
If you are gonna add this then can we abstract this to the arches and  
with somethign better than an ifdef?
The locking makes no sense in PPC (even on linux) either.

Hollis and I touched on this and has been the bane of our existence  
since we were required to have Xen interpret user level pointers,  
thread started here:
  http://lists.xensource.com/archives/html/xen-devel/2005-08/ 
msg00719.html
I cannot speak for Hollis (I think he may actually disagree with me)  
but see this as an opportunity to design something better, or at  
least have the debat (again).
What might be a better alternative an to actually have an allocate  
call rather than an mlock call where the arches and OSes could to  
what is best for them.
So what is done on x86 could be:
  do { x = alloca(len); mlock (x, len); } while (0)

but where solaris and other arches could do something more.


BTW: John, how do you solve the minor faults?!

-JX



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