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

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

ranjith krishnan <ranjithkrishnan1@xxxxxxxxx> 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@xxxxxxxxx> 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. 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel