Hello, I was posting a couple weeks back here, asking questions about getting DomUs working in Xen when installing Xen from source. Well, I have managed to get things working. Currently my setup is like this now. Xen 4.2.2, installed from source, Fedora 18 Dom0 x86_64, Debian 6 PV DomU x86_64, and Ubuntu 12.04 HVM DomU x86_64. My processor has Intel VT-X enabled. I used xl/xm to create DomUs. I was unable to get virt-manager working to create guests. I faced a similar problem with Xen 4.1 and Fedora 17 earlier. As the next step in my project, I want to log some system call information. Basically, every time a system call is made in my PV DomU, I just want to print a line like "System call made from DomU, systemcall id = xx". That is all I need for now. I have some questions regarding the same. 1. This might be a stupid question, but here goes. After I modify source code, should I do the whole compilation/install process to see my changes. ie. should i do "make and install xen, tools and stubdom" or will "make and install xen" suffice ? 2. How is the system call flow happening in Xen? Where in the code is the system call being intercepted by the hypervisor for a PV DomU. ? I found some information from this paper, http://hal.archives-ouvertes.fr/docs/00/43/10/31/PDF/Technical_Report_Syscall_Interception.pdf but still am not clear about the whole picture. Is there documentation available explaining for how system calls are handled in Xen ? The Xen code is quite large, and I am sorry to say I get lost reading it without some kind of knowledge. 3. How to log data? I see printk statements in the code. Are printk statements tied to a certain logging level ? Should I add "loglvl=all guest_loglvl=all" to my Dom0 grub to see the output from printk statements ? Also, which output file should I be seeing for my scenario? /var/log/xen/xend.log ? I apologize for the long email. Please take some time out and kindly reply. -- Ranjith krishnan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
ranjith krishnan
2013-Jul-17 00:19 UTC
Re: How to log system calls from a PV DomU under Xen
Bumping up. Can somebody give me some pointers. Would help me a lot. Thanks, Ranjith On Tue, Jul 16, 2013 at 1:34 AM, ranjith krishnan < ranjithkrishnan1@gmail.com> wrote:> Hello, > > I was posting a couple weeks back here, asking questions about getting > DomUs working in Xen when installing Xen from source. > > Well, I have managed to get things working. Currently my setup is like > this now. > Xen 4.2.2, installed from source, > Fedora 18 Dom0 x86_64, Debian 6 PV DomU x86_64, and Ubuntu 12.04 HVM DomU > x86_64. > My processor has Intel VT-X enabled. > > I used xl/xm to create DomUs. I was unable to get virt-manager working to > create guests. > I faced a similar problem with Xen 4.1 and Fedora 17 earlier. > > As the next step in my project, I want to log some system call > information. > > Basically, every time a system call is made in my PV DomU, I just want to > print a line like "System call made from DomU, systemcall id = xx". That is > all I need for now. > > I have some questions regarding the same. > 1. This might be a stupid question, but here goes. > After I modify source code, should I do the whole compilation/install > process to see my changes. > ie. should i do "make and install xen, tools and stubdom" or will "make > and install xen" suffice ? > > 2. How is the system call flow happening in Xen? > Where in the code is the system call being intercepted by the hypervisor > for a PV DomU. ? > > I found some information from this paper, > http://hal.archives-ouvertes.fr/docs/00/43/10/31/PDF/Technical_Report_Syscall_Interception.pdf > > but still am not clear about the whole picture. > > Is there documentation available explaining for how system calls are > handled in Xen ? > The Xen code is quite large, and I am sorry to say I get lost reading it > without some kind of knowledge. > > 3. How to log data? > I see printk statements in the code. Are printk statements tied to a > certain logging level ? Should I add "loglvl=all guest_loglvl=all" to my > Dom0 grub to see the output from printk statements ? > Also, which output file should I be seeing for my scenario? > /var/log/xen/xend.log ? > > I apologize for the long email. > Please take some time out and kindly reply. > > > -- > Ranjith krishnan >-- Ranjith krishnan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Konrad Rzeszutek Wilk
2013-Jul-17 00:24 UTC
Re: How to log system calls from a PV DomU under Xen
ranjith krishnan <ranjithkrishnan1@gmail.com> wrote:>Bumping up. >Can somebody give me some pointers. Would help me a lot. > >Thanks, >Ranjith > > >On Tue, Jul 16, 2013 at 1:34 AM, ranjith krishnan < >ranjithkrishnan1@gmail.com> wrote: > >> Hello, >> >> I was posting a couple weeks back here, asking questions about >getting >> DomUs working in Xen when installing Xen from source. >> >> Well, I have managed to get things working. Currently my setup is >like >> this now. >> Xen 4.2.2, installed from source, >> Fedora 18 Dom0 x86_64, Debian 6 PV DomU x86_64, and Ubuntu 12.04 HVM >DomU >> x86_64. >> My processor has Intel VT-X enabled. >> >> I used xl/xm to create DomUs. I was unable to get virt-manager >working to >> create guests. >> I faced a similar problem with Xen 4.1 and Fedora 17 earlier. >> >> As the next step in my project, I want to log some system call >> information. >> >> Basically, every time a system call is made in my PV DomU, I just >want to >> print a line like "System call made from DomU, systemcall id = xx". >That is >> all I need for now. >> >> I have some questions regarding the same. >> 1. This might be a stupid question, but here goes. >> After I modify source code, should I do the whole compilation/install >> process to see my changes. >> ie. should i do "make and install xen, tools and stubdom" or will >"make >> and install xen" suffice ? >> >> 2. How is the system call flow happening in Xen? >> Where in the code is the system call being intercepted by the >hypervisor >> for a PV DomU. ? >> >> I found some information from this paper, >> >http://hal.archives-ouvertes.fr/docs/00/43/10/31/PDF/Technical_Report_Syscall_Interception.pdf >> >> but still am not clear about the whole picture. >> >> Is there documentation available explaining for how system calls are >> handled in Xen ? >> The Xen code is quite large, and I am sorry to say I get lost reading >it >> without some kind of knowledge. >> >> 3. How to log data? >> I see printk statements in the code. Are printk statements tied to a >> certain logging level ? Should I add "loglvl=all guest_loglvl=all" to >my >> Dom0 grub to see the output from printk statements ? >> Also, which output file should I be seeing for my scenario? >> /var/log/xen/xend.log ? >> >> I apologize for the long email. >> Please take some time out and kindly reply. >> >> >> -- >> Ranjith krishnan >>Xentrace and xenalyze are your friends for this.
> 2. How is the system call flow happening in Xen? > Where in the code is the system call being intercepted by the hypervisor > for a PV DomU. ? > > I found some information from this paper, > http://hal.archives-ouvertes.fr/docs/00/43/10/31/PDF/Technical_Report_Syscall_Interception.pdf > > but still am not clear about the whole picture. > > Is there documentation available explaining for how system calls are handled > in Xen ? > The Xen code is quite large, and I am sorry to say I get lost reading it > without some kind of knowledge.Take a look at ENTRY(syscall_enter) in xen/arch/x86/x86_64/entry.S .