Re: [Fedora-xen] How to log system calls from a PV DomU under Xen

[ranjith krishnan]

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(a)gmail.com&gt; 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_Sys...
>
>  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