[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Qemu-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching
Ian Campbell <Ian.Campbell@xxxxxxxxxx> writes: > On Wed, 2013-10-16 at 12:49 +0200, Markus Armbruster wrote: >> Ian Campbell <Ian.Campbell@xxxxxxxxxx> writes: >> >> > On Wed, 2013-10-16 at 10:54 +0100, Jan Beulich wrote: >> >> >>> On 16.10.13 at 08:30, "Gonglei (Arei)" <arei.gonglei@xxxxxxxxxx> >> >> >>> 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 $(call move-if-changed,$@.tmp,$@). There are a bunch of examples in >> > tools/libxl/Makefile and elsewhere. >> >> Quoting the GNU make manual[*]: >> >> So generally the right thing to do is to delete the target file if >> the recipe fails after beginning to change the file. make will do >> this if .DELETE_ON_ERROR appears as a target. This is almost always >> what you want make to do, but it is not historical practice; so for >> compatibility, you must explicitly request it. >> >> In my opinion, every Makefile should request it. >> >> [*] https://www.gnu.org/software/make/manual/html_node/Errors.html > > I think this is somewhat orthogonal to the use of move-if-changed which > is there to ensure that the timestamp doesn't change gratuitously and > cause a load of knock on rebuilds even though the regenerated content is > identical. Yes. I was latching onto the "if someone hits Ctrl-C in the middle of this, you'll have a modified but incomplete generated file" phrase. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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