Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching

[Ian Campbell]

On Wed, 2013-10-16 at 10:54 +0100, Jan Beulich wrote:
> >>> On 16.10.13 at 08:30, "Gonglei (Arei)" <address@hidden> wrote:
> > --- hvmloader/acpi/Makefile 2013-10-16 11:51:53.000000000 +0800
> > +++ hvmloader_new//acpi/Makefile    2013-10-16 11:51:58.000000000 +0800
> > @@ -36,18 +36,34 @@
> >  
> >  dsdt_anycpu_qemu_xen.asl: dsdt.asl mk_dsdt
> >     awk 'NR > 1 {print s} {s=$$0}' $< > $@
> > -   ./mk_dsdt --dm-version qemu-xen >> $@
> > +   sed -i 's/AmlCode/dsdt_anycpu_qemu_xen/g' $@
> 
> This must never be done - if someone hits Ctrl-C in the middle of
> this, you'll have a modified but incomplete generated file. You
> either need to use properly chained rules, or do all output to a
> temporary file which you rename as the last step.
> 
> I realize that the problem existed before your change, but you
> making it worse requires doing it properly now.

The correct way to do this is to generate to a temporary file and then
use $(call move-if-changed,address@hidden,$@). There are a bunch of examples in
tools/libxl/Makefile and elsewhere.

Ian.