发件人： zhunxun@gmail.com

发送时间： 2016-10-23 17:42

收件人： berrange

主题： Re: Re: [libvirt] How libvirt address qemu command line args

Thanks，However,I have to use this method.Now I wander how get the VM xml contents in Libvirt source code,I try output some message in qemuProcessStart function like this ,but I get nothing,anyone can help me??

thanks!

my code is :

in qemuStartProcess function

char *str=qemuDomainDefFormatXML(driver, vm->def, 0);
        FILE *op=fopen("/root/libvirt.log","a");
        if(op!=NULL){
                if(str!=NULL)
                        fprintf(op,"str----cmd : %s\n",str);
                else
                        fprintf(op,"str is null\n");
                fclose(op);
        }else{
                fprintf(op,"open file error!\n");
        }

---

zhunxun@gmail.com

 

From: Daniel P. Berrange

Date: 2016-10-19 15:35

To: Michal Privoznik

CC: zhunxun@gmail.com; libvir-list

Subject: Re: [libvirt] How libvirt address qemu command line args

On Wed, Oct 19, 2016 at 10:17:21AM +0800, Michal Privoznik wrote:

> On 18.10.2016 14:59, zhunxun@gmail.com wrote:

> > Now I want to add some args about TPM  to domain's XML,so I can start a domain by virt-manager or other virsh command,and then ,I would like to use sVIrt security context to label vTPM and correspondingVM,But I do not know how to get these XML  args in libvirt.

> > the key problem is that how can i get and recognize these args!!!

> > related XML content :

>

> Usually, grepping the code for cmd name <-> XML element/attribute

> translation is sufficient (esp. if you grep tests/)

>

> >

> > <qemu:commandline>

> >     <qemu:arg value='-enable-kvm'/>

>

> Firstly, this is obsolete in favour of "-machine accel=kvm". In any

> case, <domain type='kvm'/> will do the trick (libvirt will use whatever

> is supported by qemu binary in your system).

>

> >     <qemu:arg value='-drive'/>

> >     <qemu:arg value='file=/root/nvram_2.0-jin.qcow2,if=none,id=nvram0-0-0,format=qcow2'/>

>

> Okay, this is not supported by libvirt yet. We don't really have a way

> how to specify NVRAM in anything other than a raw file. BTW: isn't qcow

> too big gun for NVRAM? I mean, NVRAM has a fixed size of what ~190 KB?

> QCOW header is about the same size.

>

> >     <qemu:arg value='-device'/>

> >     <qemu:arg value='tpm-tis,tpmdev=tpm-tpm0,id=tpm0'/>

> >     <qemu:arg value='-tpmdev'/>

> >     <qemu:arg value='libtpms,id=tpm-tpm0,nvram=nvram0-0-0,startup=clear'/>

>

> I'm not sure there's a way how to put startup=clean on the cmd line. I'm

> not even sure what it does.

> And I have not idea what libtpms is either :-)

>

> >     <qemu:arg value='-bios'/>

> >     <qemu:arg value='/root/xenSeabios/out/bios.bin'/>

> >   </qemu:commandline>

> >

 

On top of all that - QEMU is likely to fail to start since libvirt by

default runs it as qemu:qemu user/group, and so it won't have permission

to read any of the files in /root. If you have selinux/apparmour that

will also block permission.

 

This is an example of why usage of qemu:commandline is discouraged - it

will always have problems with permissions if you pass files using it.

 

Regards,

Daniel

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