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Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching |
Date: |
Wed, 16 Oct 2013 13:10:55 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
Ian Campbell <address@hidden> writes:
> On Wed, 2013-10-16 at 12:49 +0200, Markus Armbruster wrote:
>> Ian Campbell <address@hidden> writes:
>>
>> > 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.
>>
>> 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.
- [Qemu-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Gonglei (Arei), 2013/10/16
- Re: [Qemu-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Fabio Fantoni, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Ian Campbell, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Jan Beulich, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Ian Campbell, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Markus Armbruster, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Ian Campbell, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching,
Markus Armbruster <=
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Jan Beulich, 2013/10/16
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Gonglei (Arei), 2013/10/22
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Jan Beulich, 2013/10/22
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Gonglei (Arei), 2013/10/24
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Fabio Fantoni, 2013/10/24
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Gonglei (Arei), 2013/10/24
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Jan Beulich, 2013/10/28
- Re: [Qemu-devel] [Xen-devel] Hvmloader: Modify ACPI to only supply _EJ0 methods for PCIslots that support hotplug by runtime patching, Gonglei (Arei), 2013/10/28