Re: [Qemu-devel] [PATCH 03/12] Switch build system to accompanied kernel headers

[Jan Kiszka]

On 2011-06-22 22:51, Stefan Weil wrote:
> Am 08.06.2011 16:10, schrieb Jan Kiszka:
>> This helps reducing our build-time checks for feature support in the
>> available Linux kernel headers. And it helps users that do not have
>> sufficiently recent headers installed on their build machine.
>>
>> Consequently, the patch removes and build-time checks for kvm and vhost
>> in configure, the --kerneldir switch, and KVM_CFLAGS. Kernel headers are
>> supposed to be provided by QEMU only.
>>
>> s390 needs some extra love as it carries redefinitions from kernel
>> headers.
>>
>> CC: Alexander Graf <address@hidden>
>> Signed-off-by: Jan Kiszka <address@hidden>
>> ---
>> Makefile.target | 4 +-
>> configure | 151 ++++++----------------------------------------
>> target-s390x/cpu.h | 10 ---
>> target-s390x/op_helper.c | 1 +
>> 4 files changed, 21 insertions(+), 145 deletions(-)
>>
>> diff --git a/Makefile.target b/Makefile.target
>> index 5c22df8..be9c0e8 100644
>> --- a/Makefile.target
>> +++ b/Makefile.target
>> @@ -14,7 +14,7 @@ endif
>>
>> TARGET_PATH=$(SRC_PATH)/target-$(TARGET_BASE_ARCH)
>> $(call set-vpath, $(SRC_PATH):$(TARGET_PATH):$(SRC_PATH)/hw)
>> -QEMU_CFLAGS+= -I.. -I$(TARGET_PATH) -DNEED_CPU_H
>> +QEMU_CFLAGS+= -I.. -I../linux-headers -I$(TARGET_PATH) -DNEED_CPU_H
>>
>> include $(SRC_PATH)/Makefile.objs
>>
>> @@ -37,8 +37,6 @@ ifndef CONFIG_HAIKU
>> LIBS+=-lm
>> endif
>>
>> -kvm.o kvm-all.o vhost.o vhost_net.o kvmclock.o:
>> QEMU_CFLAGS+=$(KVM_CFLAGS)
>> -
>> config-target.h: config-target.h-timestamp
>> config-target.h-timestamp: config-target.mak
>>
>> diff --git a/configure b/configure
>> index d38b952..0e1dc46 100755
>> --- a/configure
>> +++ b/configure
>> @@ -113,8 +113,7 @@ curl=""
>> curses=""
>> docs=""
>> fdt=""
>> -kvm=""
>> -kvm_para=""
>> +kvm="yes"
>> nptl=""
> 
> Are you planning to add kvm support for all platforms which don't
> support it today?

That would mean replacing all their kernels with Linux. Will take a bit
longer.

I simply overshot with my cleanups:

diff --git a/configure b/configure
index 3286e33..e6847c4 100755
--- a/configure
+++ b/configure
@@ -113,7 +113,7 @@ curl=""
 curses=""
 docs=""
 fdt=""
-kvm="yes"
+kvm=""
 nptl=""
 sdl=""
 vnc="yes"
@@ -129,7 +129,7 @@ xen=""
 xen_ctrl_version=""
 linux_aio=""
 attr=""
-vhost_net="yes"
+vhost_net=""
 xfs=""

 gprof="no"
@@ -457,6 +457,8 @@ Haiku)
   linux="yes"
   linux_user="yes"
   usb="linux"
+  kvm="yes"
+  vhost_net="yes"
   if [ "$cpu" = "i386" -o "$cpu" = "x86_64" ] ; then
     audio_possible_drivers="$audio_possible_drivers fmod"
   fi

Will post this as a patch tomorrow.

> If not, kvm="yes" should be restricted to platforms with kvm support.
> 
> Otherwise, QEMU builds will fail very early:
> 
>  ERROR: Host kernel lacks signalfd() support,
>  but KVM depends on it when the IO thread is disabled.
> 
> Of course, users of those non-kvm platforms can set --disable-kvm,
> but I don't think that is the correct solution.
> 
> Even with kvm disabled, builds still fail for non-kvm systems:
> 
>  In file included from /qemu/hw/kvmclock.c:21:
>  /qemu/linux-headers/linux/kvm_para.h:26:26: warning: asm/kvm_para.h: No
> such file or directory

That indicates symlink emulation under Windows does not support
directories. Can you confirm this (check what
<builddir>/linux-headers/asm became)? Then we would have to link all
files in the arch header dir individually.

Jan

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