[Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Anthony Liguori]

I think I understand enough of what's going on in these rules to ensure this is
right.  But I could certainly use a second or third opinion...

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
v1 -> v2
 - Remove unnecessary includes (Andreas)
 - Add a sub makefile for hw/kvm (Andreas)
---
 Makefile              |    4 ++--
 Makefile.dis          |    2 +-
 Makefile.target       |    2 +-
 Makefile.user         |    2 +-
 hw/i386/Makefile.objs |    2 +-
 hw/kvm/Makefile.objs  |    1 +
 rules.mak             |    1 +
 7 files changed, 8 insertions(+), 6 deletions(-)
 create mode 100644 hw/kvm/Makefile.objs

diff --git a/Makefile b/Makefile
index cce45fb..593bd9b 100644
--- a/Makefile
+++ b/Makefile
@@ -405,5 +405,5 @@ tar:
 Makefile: $(GENERATED_HEADERS)
 
 # Include automatically generated dependency files
--include $(wildcard *.d audio/*.d slirp/*.d block/*.d net/*.d ui/*.d qapi/*.d)
--include $(wildcard qga/*.d hw/*.d hw/usb/*.d qom/*.d)
+# All subdir dependencies come automatically from our recursive subdir rules
+-include $(wildcard *.d)
diff --git a/Makefile.dis b/Makefile.dis
index 3e1fcaf..09060f0 100644
--- a/Makefile.dis
+++ b/Makefile.dis
@@ -20,4 +20,4 @@ clean:
 	rm -f *.o *.d *.a *~
 
 # Include automatically generated dependency files
--include $(wildcard *.d */*.d)
+-include $(wildcard *.d)
diff --git a/Makefile.target b/Makefile.target
index 2907aad..550d889 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -216,4 +216,4 @@ GENERATED_HEADERS += config-target.h
 Makefile: $(GENERATED_HEADERS)
 
 # Include automatically generated dependency files
--include $(wildcard *.d */*.d)
+-include $(wildcard *.d)
diff --git a/Makefile.user b/Makefile.user
index b717820..0ffefe8 100644
--- a/Makefile.user
+++ b/Makefile.user
@@ -23,4 +23,4 @@ clean:
 	done
 
 # Include automatically generated dependency files
--include $(wildcard *.d */*.d)
+-include $(wildcard *.d)
diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
index d43f1df..eb171b7 100644
--- a/hw/i386/Makefile.objs
+++ b/hw/i386/Makefile.objs
@@ -7,7 +7,7 @@ obj-y += debugcon.o multiboot.o
 obj-y += pc_piix.o
 obj-y += pc_sysfw.o
 obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
-obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
+obj-y += kvm/
 obj-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
 
 obj-y := $(addprefix ../,$(obj-y))
diff --git a/hw/kvm/Makefile.objs b/hw/kvm/Makefile.objs
new file mode 100644
index 0000000..226497a
--- /dev/null
+++ b/hw/kvm/Makefile.objs
@@ -0,0 +1 @@
+obj-$(CONFIG_KVM) += clock.o apic.o i8259.o ioapic.o i8254.o
diff --git a/rules.mak b/rules.mak
index 4bc5e52..60f3e96 100644
--- a/rules.mak
+++ b/rules.mak
@@ -94,6 +94,7 @@ define unnest-dir
 $(foreach var,$(nested-vars),$(call push-var,$(var),$1/))
 $(eval obj := $(obj)/$1)
 $(eval include $(SRC_PATH)/$1/Makefile.objs)
+$(eval -include $(wildcard $1/*.d))
 $(eval obj := $(patsubst %/$1,%,$(obj)))
 $(foreach var,$(nested-vars),$(call pop-var,$(var),$1/))
 endef
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Andreas Färber]

Am 18.06.2012 02:01, schrieb Anthony Liguori:
> I think I understand enough of what's going on in these rules to ensure this is
> right.  But I could certainly use a second or third opinion...
> 
> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
> ---
> v1 -> v2
>  - Remove unnecessary includes (Andreas)
>  - Add a sub makefile for hw/kvm (Andreas)
> ---
>  Makefile              |    4 ++--
>  Makefile.dis          |    2 +-
>  Makefile.target       |    2 +-
>  Makefile.user         |    2 +-
>  hw/i386/Makefile.objs |    2 +-
>  hw/kvm/Makefile.objs  |    1 +
>  rules.mak             |    1 +
>  7 files changed, 8 insertions(+), 6 deletions(-)
>  create mode 100644 hw/kvm/Makefile.objs
> 
> diff --git a/Makefile b/Makefile
> index cce45fb..593bd9b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -405,5 +405,5 @@ tar:
>  Makefile: $(GENERATED_HEADERS)
>  
>  # Include automatically generated dependency files
> --include $(wildcard *.d audio/*.d slirp/*.d block/*.d net/*.d ui/*.d qapi/*.d)
> --include $(wildcard qga/*.d hw/*.d hw/usb/*.d qom/*.d)
> +# All subdir dependencies come automatically from our recursive subdir rules
> +-include $(wildcard *.d)
> diff --git a/Makefile.dis b/Makefile.dis
> index 3e1fcaf..09060f0 100644
> --- a/Makefile.dis
> +++ b/Makefile.dis
> @@ -20,4 +20,4 @@ clean:
>  	rm -f *.o *.d *.a *~
>  
>  # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/Makefile.target b/Makefile.target
> index 2907aad..550d889 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -216,4 +216,4 @@ GENERATED_HEADERS += config-target.h
>  Makefile: $(GENERATED_HEADERS)
>  
>  # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/Makefile.user b/Makefile.user
> index b717820..0ffefe8 100644
> --- a/Makefile.user
> +++ b/Makefile.user
> @@ -23,4 +23,4 @@ clean:
>  	done
>  
>  # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
> index d43f1df..eb171b7 100644
> --- a/hw/i386/Makefile.objs
> +++ b/hw/i386/Makefile.objs
> @@ -7,7 +7,7 @@ obj-y += debugcon.o multiboot.o
>  obj-y += pc_piix.o
>  obj-y += pc_sysfw.o
>  obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
> -obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
> +obj-y += kvm/

This will work technically but I still feel this is wrong semantically.
The pre-Paolo and current way is picking specific files from the hw/kvm/
directory. Your change above implies that in hw/kvm/ only x86 files can
live, which I dislike. As suggested before, I would prefer if x86-only
files were moved to an x86-specific location - the place for that
existing since Paolo's refactoring would be hw/i386/. CC'ing Jan. That
would match Paolo's reply in the unicore32 thread on future file
placement. Alternatives would be hw/i386/kvm/ or hw/kvm/i386/; we're
talking about a handful of files only though, so I don't think they
require a new subdirectory.

Andreas

>  obj-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
>  
>  obj-y := $(addprefix ../,$(obj-y))
> diff --git a/hw/kvm/Makefile.objs b/hw/kvm/Makefile.objs
> new file mode 100644
> index 0000000..226497a
> --- /dev/null
> +++ b/hw/kvm/Makefile.objs
> @@ -0,0 +1 @@
> +obj-$(CONFIG_KVM) += clock.o apic.o i8259.o ioapic.o i8254.o
> diff --git a/rules.mak b/rules.mak
> index 4bc5e52..60f3e96 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -94,6 +94,7 @@ define unnest-dir
>  $(foreach var,$(nested-vars),$(call push-var,$(var),$1/))
>  $(eval obj := $(obj)/$1)
>  $(eval include $(SRC_PATH)/$1/Makefile.objs)
> +$(eval -include $(wildcard $1/*.d))
>  $(eval obj := $(patsubst %/$1,%,$(obj)))
>  $(foreach var,$(nested-vars),$(call pop-var,$(var),$1/))
>  endef

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Jan Kiszka]

On 2012-06-18 02:32, Andreas Färber wrote:
> Am 18.06.2012 02:01, schrieb Anthony Liguori:
>> I think I understand enough of what's going on in these rules to ensure this is
>> right.  But I could certainly use a second or third opinion...
>>
>> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
>> ---
>> v1 -> v2
>>  - Remove unnecessary includes (Andreas)
>>  - Add a sub makefile for hw/kvm (Andreas)
>> ---
>>  Makefile              |    4 ++--
>>  Makefile.dis          |    2 +-
>>  Makefile.target       |    2 +-
>>  Makefile.user         |    2 +-
>>  hw/i386/Makefile.objs |    2 +-
>>  hw/kvm/Makefile.objs  |    1 +
>>  rules.mak             |    1 +
>>  7 files changed, 8 insertions(+), 6 deletions(-)
>>  create mode 100644 hw/kvm/Makefile.objs
>>
>> diff --git a/Makefile b/Makefile
>> index cce45fb..593bd9b 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -405,5 +405,5 @@ tar:
>>  Makefile: $(GENERATED_HEADERS)
>>  
>>  # Include automatically generated dependency files
>> --include $(wildcard *.d audio/*.d slirp/*.d block/*.d net/*.d ui/*.d qapi/*.d)
>> --include $(wildcard qga/*.d hw/*.d hw/usb/*.d qom/*.d)
>> +# All subdir dependencies come automatically from our recursive subdir rules
>> +-include $(wildcard *.d)
>> diff --git a/Makefile.dis b/Makefile.dis
>> index 3e1fcaf..09060f0 100644
>> --- a/Makefile.dis
>> +++ b/Makefile.dis
>> @@ -20,4 +20,4 @@ clean:
>>  	rm -f *.o *.d *.a *~
>>  
>>  # Include automatically generated dependency files
>> --include $(wildcard *.d */*.d)
>> +-include $(wildcard *.d)
>> diff --git a/Makefile.target b/Makefile.target
>> index 2907aad..550d889 100644
>> --- a/Makefile.target
>> +++ b/Makefile.target
>> @@ -216,4 +216,4 @@ GENERATED_HEADERS += config-target.h
>>  Makefile: $(GENERATED_HEADERS)
>>  
>>  # Include automatically generated dependency files
>> --include $(wildcard *.d */*.d)
>> +-include $(wildcard *.d)
>> diff --git a/Makefile.user b/Makefile.user
>> index b717820..0ffefe8 100644
>> --- a/Makefile.user
>> +++ b/Makefile.user
>> @@ -23,4 +23,4 @@ clean:
>>  	done
>>  
>>  # Include automatically generated dependency files
>> --include $(wildcard *.d */*.d)
>> +-include $(wildcard *.d)
>> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
>> index d43f1df..eb171b7 100644
>> --- a/hw/i386/Makefile.objs
>> +++ b/hw/i386/Makefile.objs
>> @@ -7,7 +7,7 @@ obj-y += debugcon.o multiboot.o
>>  obj-y += pc_piix.o
>>  obj-y += pc_sysfw.o
>>  obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
>> -obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
>> +obj-y += kvm/
> 
> This will work technically but I still feel this is wrong semantically.
> The pre-Paolo and current way is picking specific files from the hw/kvm/
> directory. Your change above implies that in hw/kvm/ only x86 files can
> live, which I dislike. As suggested before, I would prefer if x86-only
> files were moved to an x86-specific location - the place for that
> existing since Paolo's refactoring would be hw/i386/. CC'ing Jan. That
> would match Paolo's reply in the unicore32 thread on future file
> placement. Alternatives would be hw/i386/kvm/ or hw/kvm/i386/; we're
> talking about a handful of files only though, so I don't think they
> require a new subdirectory.

Some per-arch separation is required, at least in the build process.
We'll see power and arm stubs for in-kernel devices soon.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Peter Maydell]

On 18 June 2012 10:13, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> On 2012-06-18 02:32, Andreas Färber wrote:
>> This will work technically but I still feel this is wrong semantically.
>> The pre-Paolo and current way is picking specific files from the hw/kvm/
>> directory. Your change above implies that in hw/kvm/ only x86 files can
>> live, which I dislike.

> Some per-arch separation is required, at least in the build process.
> We'll see power and arm stubs for in-kernel devices soon.

Indeed -- I have a hw/kvm/arm_gic.c in the qemu-linaro tree, so
if you break building that I'll have to unbreak it :-)

(Does architecture-specific separation make much sense in general?
Not all devices are architecture-specific. I'd have thought that
a functional split eg timer/serial/usb like the linux kernel layout
would be better.)

-- PMM

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Andreas Färber]

Am 18.06.2012 11:31, schrieb Peter Maydell:
> On 18 June 2012 10:13, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> On 2012-06-18 02:32, Andreas Färber wrote:
>>> This will work technically but I still feel this is wrong semantically.
>>> The pre-Paolo and current way is picking specific files from the hw/kvm/
>>> directory. Your change above implies that in hw/kvm/ only x86 files can
>>> live, which I dislike.
> 
>> Some per-arch separation is required, at least in the build process.
>> We'll see power and arm stubs for in-kernel devices soon.
> 
> Indeed -- I have a hw/kvm/arm_gic.c in the qemu-linaro tree, so
> if you break building that I'll have to unbreak it :-)
> 
> (Does architecture-specific separation make much sense in general?
> Not all devices are architecture-specific. I'd have thought that
> a functional split eg timer/serial/usb like the linux kernel layout
> would be better.)

Maybe you're misreading me? I was saying iff a device is specifically
(not accidentally) for one target foo then it may/should be placed into
hw/foo/ directory.

We already have a hw/usb/ directory, and as long as there are no target
dependencies and sufficient files I see nothing wrong with hw/timer/ or
hw/serial/.

Cheers,
Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Peter Maydell]

On 18 June 2012 11:42, Andreas Färber <afaerber@suse.de> wrote:
> Am 18.06.2012 11:31, schrieb Peter Maydell:
>> (Does architecture-specific separation make much sense in general?
>> Not all devices are architecture-specific. I'd have thought that
>> a functional split eg timer/serial/usb like the linux kernel layout
>> would be better.)
>
> Maybe you're misreading me? I was saying iff a device is specifically
> (not accidentally) for one target foo then it may/should be placed into
> hw/foo/ directory.

Yes, I'm saying that seems like a confusing split, because a few
devices for target foo will be in hw/foo and a number more in hw/,
and there'll probably be cases where something in hw/foo has to
move out into hw/ when a new target comes along that happens to
reuse it. So rather than having hw/foo where foo == target-name,
I'm suggesting hw/foo where foo == kind-of-device. As you say
we've already moved a bit down this road with usb, for instance.

-- PMM

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Andreas Färber]

Am 18.06.2012 12:56, schrieb Peter Maydell:
> On 18 June 2012 11:42, Andreas Färber <afaerber@suse.de> wrote:
>> Am 18.06.2012 11:31, schrieb Peter Maydell:
>>> (Does architecture-specific separation make much sense in general?
>>> Not all devices are architecture-specific. I'd have thought that
>>> a functional split eg timer/serial/usb like the linux kernel layout
>>> would be better.)
>>
>> Maybe you're misreading me? I was saying iff a device is specifically
>> (not accidentally) for one target foo then it may/should be placed into
>> hw/foo/ directory.
> 
> Yes, I'm saying that seems like a confusing split, because a few
> devices for target foo will be in hw/foo and a number more in hw/,
> and there'll probably be cases where something in hw/foo has to
> move out into hw/ when a new target comes along that happens to
> reuse it. So rather than having hw/foo where foo == target-name,
> I'm suggesting hw/foo where foo == kind-of-device. As you say
> we've already moved a bit down this road with usb, for instance.

But the point is that hw/foo/ is required for the new Makefile system,
so we have the empty folders anyway, whereas putting target-specific
stuff into, e.g., hw/apic/ will not solve the dependency issue that I
tracked down here.
If you do have an automated solution to that, please spill it out. :)

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Peter Maydell]

On 18 June 2012 12:35, Andreas Färber <afaerber@suse.de> wrote:
> But the point is that hw/foo/ is required for the new Makefile system,
> so we have the empty folders anyway, whereas putting target-specific
> stuff into, e.g., hw/apic/ will not solve the dependency issue that I
> tracked down here.

Why should our makefile system mandate empty directories in the
source tree hierarchy? That seems like a bug to me...

-- PMM

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Anthony Liguori]

On 06/18/2012 04:13 AM, Jan Kiszka wrote:
> On 2012-06-18 02:32, Andreas Färber wrote:
>> Am 18.06.2012 02:01, schrieb Anthony Liguori:
>> This will work technically but I still feel this is wrong semantically.
>> The pre-Paolo and current way is picking specific files from the hw/kvm/
>> directory. Your change above implies that in hw/kvm/ only x86 files can
>> live, which I dislike. As suggested before, I would prefer if x86-only
>> files were moved to an x86-specific location - the place for that
>> existing since Paolo's refactoring would be hw/i386/. CC'ing Jan. That
>> would match Paolo's reply in the unicore32 thread on future file
>> placement. Alternatives would be hw/i386/kvm/ or hw/kvm/i386/; we're
>> talking about a handful of files only though, so I don't think they
>> require a new subdirectory.
>
> Some per-arch separation is required, at least in the build process.
> We'll see power and arm stubs for in-kernel devices soon.

i8259.o i8254.o ioapic.o don't need to be arch specific

apic.o ought to be renamed to lapic.o and moved to target-i386/kvm/

I think clock.o also more than likely belongs in target-i386/kvm/.  It would 
have to be implemented as part of the CPU core if it ever existed IRL.

In general, if is logically part of a CPU core, it ought to be in 
target-$(ARCH).  Otherwise, it shouldn't be built as a target specific object.

Regards,

Anthony Liguori

> Jan
>

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Jan Kiszka]

On 2012-06-18 14:47, Anthony Liguori wrote:
> On 06/18/2012 04:13 AM, Jan Kiszka wrote:
>> On 2012-06-18 02:32, Andreas Färber wrote:
>>> Am 18.06.2012 02:01, schrieb Anthony Liguori:
>>> This will work technically but I still feel this is wrong semantically.
>>> The pre-Paolo and current way is picking specific files from the hw/kvm/
>>> directory. Your change above implies that in hw/kvm/ only x86 files can
>>> live, which I dislike. As suggested before, I would prefer if x86-only
>>> files were moved to an x86-specific location - the place for that
>>> existing since Paolo's refactoring would be hw/i386/. CC'ing Jan. That
>>> would match Paolo's reply in the unicore32 thread on future file
>>> placement. Alternatives would be hw/i386/kvm/ or hw/kvm/i386/; we're
>>> talking about a handful of files only though, so I don't think they
>>> require a new subdirectory.
>>
>> Some per-arch separation is required, at least in the build process.
>> We'll see power and arm stubs for in-kernel devices soon.
> 
> i8259.o i8254.o ioapic.o don't need to be arch specific

In theory. In practice they carry quite a bit of the PC architecture
(i8254: HPET and PC speaker port, i8259: ELCR). Maybe not the IOAPIC. It
was once reused on IA64, but that arch is dead.

> 
> apic.o ought to be renamed to lapic.o and moved to target-i386/kvm/

"apic" is fine as name as the code covers both cases.

Should be move hw/apic* as well?

> 
> I think clock.o also more than likely belongs in target-i386/kvm/.  It would 
> have to be implemented as part of the CPU core if it ever existed IRL.
> 
> In general, if is logically part of a CPU core, it ought to be in 
> target-$(ARCH).  Otherwise, it shouldn't be built as a target specific object.

There are some practical things like lacking types or defines in the KVM
API that most probably prevent building certain KVM devices for all
targets unconditionally.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [PATCH] make: automatically include dependencies in recursive subdir rules (v2)

[Anthony Liguori]

On 06/17/2012 07:01 PM, Anthony Liguori wrote:
> I think I understand enough of what's going on in these rules to ensure this is
> right.  But I could certainly use a second or third opinion...
>
> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>

Applied.

Regards,

Anthony Liguori

> ---
> v1 ->  v2
>   - Remove unnecessary includes (Andreas)
>   - Add a sub makefile for hw/kvm (Andreas)
> ---
>   Makefile              |    4 ++--
>   Makefile.dis          |    2 +-
>   Makefile.target       |    2 +-
>   Makefile.user         |    2 +-
>   hw/i386/Makefile.objs |    2 +-
>   hw/kvm/Makefile.objs  |    1 +
>   rules.mak             |    1 +
>   7 files changed, 8 insertions(+), 6 deletions(-)
>   create mode 100644 hw/kvm/Makefile.objs
>
> diff --git a/Makefile b/Makefile
> index cce45fb..593bd9b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -405,5 +405,5 @@ tar:
>   Makefile: $(GENERATED_HEADERS)
>
>   # Include automatically generated dependency files
> --include $(wildcard *.d audio/*.d slirp/*.d block/*.d net/*.d ui/*.d qapi/*.d)
> --include $(wildcard qga/*.d hw/*.d hw/usb/*.d qom/*.d)
> +# All subdir dependencies come automatically from our recursive subdir rules
> +-include $(wildcard *.d)
> diff --git a/Makefile.dis b/Makefile.dis
> index 3e1fcaf..09060f0 100644
> --- a/Makefile.dis
> +++ b/Makefile.dis
> @@ -20,4 +20,4 @@ clean:
>   	rm -f *.o *.d *.a *~
>
>   # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/Makefile.target b/Makefile.target
> index 2907aad..550d889 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -216,4 +216,4 @@ GENERATED_HEADERS += config-target.h
>   Makefile: $(GENERATED_HEADERS)
>
>   # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/Makefile.user b/Makefile.user
> index b717820..0ffefe8 100644
> --- a/Makefile.user
> +++ b/Makefile.user
> @@ -23,4 +23,4 @@ clean:
>   	done
>
>   # Include automatically generated dependency files
> --include $(wildcard *.d */*.d)
> +-include $(wildcard *.d)
> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
> index d43f1df..eb171b7 100644
> --- a/hw/i386/Makefile.objs
> +++ b/hw/i386/Makefile.objs
> @@ -7,7 +7,7 @@ obj-y += debugcon.o multiboot.o
>   obj-y += pc_piix.o
>   obj-y += pc_sysfw.o
>   obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
> -obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
> +obj-y += kvm/
>   obj-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
>
>   obj-y := $(addprefix ../,$(obj-y))
> diff --git a/hw/kvm/Makefile.objs b/hw/kvm/Makefile.objs
> new file mode 100644
> index 0000000..226497a
> --- /dev/null
> +++ b/hw/kvm/Makefile.objs
> @@ -0,0 +1 @@
> +obj-$(CONFIG_KVM) += clock.o apic.o i8259.o ioapic.o i8254.o
> diff --git a/rules.mak b/rules.mak
> index 4bc5e52..60f3e96 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -94,6 +94,7 @@ define unnest-dir
>   $(foreach var,$(nested-vars),$(call push-var,$(var),$1/))
>   $(eval obj := $(obj)/$1)
>   $(eval include $(SRC_PATH)/$1/Makefile.objs)
> +$(eval -include $(wildcard $1/*.d))
>   $(eval obj := $(patsubst %/$1,%,$(obj)))
>   $(foreach var,$(nested-vars),$(call pop-var,$(var),$1/))
>   endef