Re: [PATCH] qemu: fix configuring kvm probe when using --kerneldir

From: Andre Przywara <andre.przywara@amd.com>
To: ehrhardt@linux.vnet.ibm.com
Cc: aliguori@us.ibm.com, Avi Kivity <avi@redhat.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [PATCH] qemu: fix configuring kvm probe when using --kerneldir
Date: Fri, 9 Jan 2009 15:36:35 +0100	[thread overview]
Message-ID: <496760F3.7020902@amd.com> (raw)
In-Reply-To: <1231503054-10618-1-git-send-email-ehrhardt@linux.vnet.ibm.com>

ehrhardt@linux.vnet.ibm.com wrote:
> From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
> 
> There is already a variable kvm_cflags which gets the path of the kernel
> includes when using --kerneldir. But eventually with newer kernels we all will
> need arch/$arch/include too (my case was a incldue of asm/kvm.h which was not
> found anymore). Headers in a full kernel source are not flattened to
> one arch like they are if e.g. installed kernel headers are used.
I also stumbled over this recently (in kvm-userspace.git), but I had 
problems with the qemu part not including KVM support because in 
qemu/configure the KVM build test failed due to the missing asm/kvm.h.
I saw that --kerneldir gets not propagated to qemu, but libkvm_kerneldir 
instead, which is hardcoded to point to `pwd`/kernel. Shouldn't that be 
fixed, too?
I use kvm-userspace.git and a not-installed kernel from kvm.git for 
compiling, so I say "./configure --kerneldir=/src/kvm.git 
--with-patched-kernel". I eventually hacked KVM's configure to propagate 
--kerneldir to qemu and added arch/x86/include to the include path in 
qemu/configure. This is of course a hack (that's why I don't append it 
here), but it worked ;-)
If someone proposes a clean and easy way to solve this, I'd be happy to 
write a patch.

> To fix that, the includes added to cflags depending on --kerneldir should also
> contian the arch includes. The patch adds a special check for x86 because its
> source layout recently changed, all others directly use arch/$cpu/include if
> existent.
This is one problem I also noticed. $cpu is not the same as the Linux' 
arch name, is there a suitable variable or do we have to do a large 
switch/case?

Regards,
Andre.

> 
> Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
> ---
> 
> [diffstat]
>  configure |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> [diff]
> diff --git a/configure b/configure
> --- a/configure
> +++ b/configure
> @@ -963,6 +963,12 @@ EOF
>  EOF
>    if test "$kerneldir" != "" ; then
>        kvm_cflags=-I"$kerneldir"/include
> +      if test \( "$cpu" = "i386" -o "$cpu" = "x86_64" \) \
> +         -a -d "$kerneldir/arch/x86/include" ; then
> +            kvm_cflags="$kvm_cflags -I$kerneldir/arch/x86/include"
> +        elif test -d "$kerneldir/arch/$cpu/include" ; then
> +            kvm_cflags="$kvm_cflags -I$kerneldir/arch/$cpu/include"
> +      fi
>    else
>        kvm_cflags=""
>    fi
-- 
Andre Przywara
AMD-OSRC (Dresden)
Tel: x84917