On Tue, 9 Dec 2008 09:13:24 -0800
Greg KH <greg@xxxxxxxxx> wrote:
> On Tue, Dec 09, 2008 at 09:01:21AM -0800, Jesse Barnes wrote:
> > On Monday, December 08, 2008 11:57 pm Yuji Shimada wrote:
> > > On Fri, 5 Dec 2008 10:08:54 -0800
> > >
> > > Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> wrote:
> > > > On Thursday, December 4, 2008 12:43 am Yuji Shimada wrote:
> > > > > What do you think about supporting both boottime and runtime
> > > > > re-assignment.
> > > > >
> > > > > I find we can re-assign resources using fakephp driver. What I need to
> > > > > do is enhancing my patch to set "pagealignmem" parameter at runtime.
> > > > >
> > > > > I think it is good to create "/proc/bus/pci/pagealignmem".
> > > > >
> > > > > Re-assignment can be done as follows.
> > > > >
> > > > > 1. Sets SSSS:DD:BB.F of the device to "pagealignmem" parameter at
> > > > > runtime. 2. Hot-remove the device
> > > > > 3. Hot-add it.
> > > > >
> > > > >
> > > > > If you agree with me, I will submit new patch.
> > > >
> > > > This is a step in the right direction, thanks for pursuing it.
> > >
> > > Thanks too.
> > >
> > > > It might be better to put the pagealignmem file (and maybe just call it
> > > > "resource_alignment") into the sysfs directory for the device instead
> > > > though, then we could write various alignment constraints to it and hot
> > > > plug as you suggest.
> > >
> > > I can't put the "resource_alignment" file into sysfs directory for the
> > > device like "/sys/bus/pci/device/SSSS:BB:DD.F", because it disappears
> > > when device is hot-removed.
> >
> > Oh yeah, of course. :)
> >
> > > How about setting ALIGN@SSSS:BB:DD.F to "/sys/bus/pci/resource_alignment"?
> > > ALIGN means alignment for corresponding device.
> >
> > Yeah, that sounds better; and it keeps things out of /proc which is good.
> > Maybe other people have thoughts about it... Greg may object to having a
> > 'resource_alignment' file that might possibly contain multiple {device,
> > alignment} pairs though.
>
> Yes, that would not be good, especially as it could grow very large with
> huge machines, overflowing the size of your sysfs file buffer.
We don't have to specify all device in system. We have only to specify
the device which has smaller resource than alignment. For example,
when we want to align resource to 4KB boundary, we have to specify
device which has 256 byte resource.
Thanks,
--
Yuji Shimada
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