[libvirt] [PATCH] compile: fix undefined reference to gnutls_x509_crt_get_dn with gcc-4.6.1

[Xu He Jie]

于 2011年10月18日 22:45, Eric Blake 写道:
> On 10/18/2011 02:06 AM, Xu He Jie wrote:
>> From: soulxu<soulxu at soulxu-ThinkPad-T410.(none)>
>>
>> When I compile libvirt with gcc-4.6.1 in ubuntu 11.10, got error as 
>> below:
>>
>> CCLD libvirtd
>> /usr/bin/ld: 
>> ../src/.libs/libvirt_driver_qemu.a(libvirt_driver_qemu_la-qemu_migration.o): 
>> undefined reference to symbol 'gnutls_x509_crt_get_dn@@GNUTLS_1_4'
>> /usr/bin/ld: note: 'gnutls_x509_crt_get_dn@@GNUTLS_1_4' is defined in 
>> DSO /usr/lib/x86_64-linux-gnu/libgnutls.so so try adding it to the 
>> linker command line
>> /usr/lib/x86_64-linux-gnu/libgnutls.so: could not read symbols: 
>> Invalid operation
>> collect2: ld returned 1 exit status
>> make[3]: *** [libvirtd] Error 1
>>
>>
>> It can compile with gcc-4.5.2 in ubuntu 11.04, but it can not compile 
>> with gcc-4.6.1 in ubuntu 11.10.
>>
>> I didn't find reason. Does Anyone know the reason or the different 
>> between gcc-4.5.2 and gcc-4.6.1?
>
> More likely, the difference is not in gcc, but in ld policy - Ubuntu 
> recently changed policy to no longer allow implicit link dependencies 
> by default (that is, if A links against B, and B links against C, 
> older distros allowed A to use symbols from C without explicitly 
> linking against C, while newer distros require the explicit link).
>
>>
>> I still provide a patch for this. Just make it is working now.
>>
>> Signed-off-by: soulxu<soulxu at soulxu-ThinkPad-T410.(none)>
Just found I forgot configuring git. The Signed-off-by should be:
Signed-off-by: Xu He Jie <xuhj at linux.vnet.ibm.com>
>> ---
>> src/Makefile.am | 6 +++++-
>> 1 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index 87d91ed..104efc6 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -776,10 +776,14 @@ noinst_LTLIBRARIES += libvirt_driver_qemu.la
>> #libvirt_la_BUILT_LIBADD += libvirt_driver_qemu.la
>> endif
>> libvirt_driver_qemu_la_CFLAGS = $(NUMACTL_CFLAGS) \
>> + $(GNUTLS_CFLAGS) \
>> + $(LIBXML_CFLAGS) \
>
> I understand the addition of GNUTLS_CFLAGS, but why LIBXML_CFLAGS? Did 
> you get a second link error?
Yes, I get a second link error. When I just add GNUTLS_LIBS to there, I 
get another error, as below:

/usr/bin/ld: 
../src/.libs/libvirt_driver_qemu.a(libvirt_driver_qemu_la-qemu_domain.o): undefined 
reference to symbol 'xmlXPathRegisterNs@@LIBXML2_2.4.30'
/usr/bin/ld: note: 'xmlXPathRegisterNs@@LIBXML2_2.4.30' is defined in 
DSO /usr/lib/libxml2.so so try adding it to the linker command line
/usr/lib/libxml2.so: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make[3]: *** [libvirtd] Error 1

So I add LIBXML_CFLAGS and LIBXML_LIBS to there too.
>
>> -I at top_srcdir@/src/conf $(AM_CFLAGS)
>> libvirt_driver_qemu_la_LDFLAGS = $(AM_LDFLAGS)
>> libvirt_driver_qemu_la_LIBADD = $(NUMACTL_LIBS) \
>> - $(CAPNG_LIBS)
>> + $(CAPNG_LIBS) \
>> + $(GNUTLS_LIBS) \
>> + $(LIBXML_LIBS)
>
> Likewise.
>
> Your approach to a fix is correct, but I need to know whether to use 
> the patch as-is or whether we just need one library rather than two.
>