[Xen-devel] Follow up on the OpenIPMI in Dom0 thread

["Shureih, Tariq" <tariq.shureih@xxxxxxxxx>]

I just signed up after reading the thread discussing the OpenIPMI in Dom0 
question.

>>>>>> On Wednesday, December 07, 2005 10:54 AM,  Brian Lavender <> wrote: 
>>>>>> 
>>>>>>> If I ascertained correctly, OpenIPMI has problems. Have you
>>>>>>> tried FreeIPMI? I am not a kernel hacker, but FreeIPMI requires
>>>>>>> no kernel support. Albert Chu said they were about to add
>>>>>>> support in the Linux Kernel at Lawrence Livermore. I am about
>>>>>>> to fire up FreeIPMI. Is there some distinct advantage to
>>>>>>> OpenIPMI. I have only been using IPMI out-of- band up to this
>>>>>>> point to primarily do remote power. 
>>>>>>> 
>>>>>>> brian

FreeIPMI is just another implementation similar to OpenIPMI.
OpenIPMI, however, is the kernel-included IPMI driver in the stock
kernel. In addition OpenIPMI provides a user space library to
abstract the byte counting complexities of IPMI with a nice C
interface. FreeIPMI provides a similar library as well.
All the implementation (IPMIUtil, IPMITool, FreeIPMI, OpenIPMI) provide a set 
of tools to access the IPMI
data in the BMC. 
 
To use the BMC In-Band, you will need the kernel driver; no
Question (usually the KCS interface). I am not sure how FreeIPMI would access 
the BMC without a kernel driver and OpenIPMI is the stock-kernel Linux driver.

>>>>>>> On Tue, 2005-11-08 at 18:11 -0500, Andrew D. Ball wrote:
>>>>>>>> Has anyone had any success with the OpenIPMI kernel modules on
>>>>>>>> dom0? I've been trying to get this to work on a IBM HS20
>>>>>>>> 8843-25U blade running RHEL 4 Update 2 AS i386 (32-bit).
>>>>>>>> 

As for loading the driver in Dom0, I personally have never tried
it. I think I will need to find the time and play with it a bit to
see what's going on, but my guess from the dmesg output is that
there is no access to the hardware registers (SMBIOS or ACPI
tables) from DOM0 and the driver is unable to retrieve the KCS
port address. 
 
One thing to keep in mind, the IPMI bus and BMC are I2C devices/bus.  The IPMI 
bus is a private I2C bus which is only accessable from the BMC (acts
like an I2C controller), so it could be that Xen's DOM0 is
preventing access to it for some reason.

>>>>>>>> The code to initialize a BMC starts in the
>>>>>>>> init_one_smi() function in
>>>>>>>> linux-2.6.12-xen0/drivers/char/ipmi/ipmi_si_intf.c . I think
>>>>>>>> this code tries to send and write bytes from IO ports using
>>>>>>>> inb() and outb() and don't know whether these are known to
>>>>>>>> work with Xen or not.

This might support my above theory about access within Xen to the I2C subsystem 
and/or specific mapped memory regions?

Feedback is welcome.  I will also report back as I find out more information.


*****************
Tariq Shureih
Open Source Technology Center
Intel Corporation
Hillsboro, Oregon.
 
The greatest enemy of knowledge is not ignorance
It is the illusion of knowledge -- Steven Hawking


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