Re: qemu for bmc

["Cédric Le Goater" <clg@kaod.org>]

On 11/20/20 5:44 PM, Patrick Venture wrote:
> On Thu, Nov 19, 2020 at 8:56 AM Patrick Venture <venture@google.com> wrote:
>>
>> On Wed, Nov 18, 2020 at 11:41 PM Cédric Le Goater <clg@kaod.org> wrote:
>>>
>>> Hello,
>>>
>>> On 11/18/20 10:11 PM, Patrick Venture wrote:
>>>> Patrick;
>>>>
>>>> I was looking at a patch series of yours that landed,
>>>> https://github.com/qemu/qemu/blob/master/hw/arm/aspeed.c#L517 <-- in
>>>> this line you're referencing a device that appears to be missing from
>>>> qemu - namely, the pca i2c mux.
>>>>
>>>> My question is to the community at large, and you also, is anyone
>>>> currently implementing this i2c-mux or a similar one?
>>>
>>> I haven't seen any patches for this device on the QEMU mailing
>>> list.
>>>
>>> John Wang from Bytedance has started developing some new I2C
>>> device models for their G220A board. We hope to get that merged
>>> in 6.0.
>>>
>>> If you are interested, we maintain a brief TODO list here
>>>
>>>   https://github.com/openbmc/qemu/wiki
>>
>> Thanks, I'll take a look.
>>
>>>
>>> Feel free to update.
>>>
>>>
>>> In terms of priority, I think that the support to boot from eMMC
>>> on the AST2600 is an important one. Reviewing the FSI patches
>>> also but that's an IBM thing, so it might not interest the
>>> community that much.
>>>
>>> There are quite a few I2C models missing.
>>
>> Yes.
>>
>>>
>>> All Aspeed models could be more precise.
>>>
>>>
>>> Google and Nuvoton have merged their models for the npcm750-evb
>>> and quanta-gsj boards. It would be good to have some interaction
>>> with them, on bus/device modeling but also on full system emulation.
>>
>> Yeah, I believe you've seen my team's patches adding nuvoton support
>> to Qemu.  It's a WIP, but we're making a lot of headway and hope to
>> have more Nuvoton 730/750 qemu devices sent to qemu over the coming
>> days, weeks, etc.
>>
>> One of the big gaps that I'm seeing is that we weren't yet looking at
>> the rest of the board as closely, to see what other devices are
>> missing, such as the i2c-muxes, etc.  This will be a really good
>> community convergence point as there are only so many i2c-muxes,
>> voltage regulators, temperature sensors, that are in common use.
>>
>> I'll go through some of our plans as stated and add them to the todo
>> list.  My team currently isn't focused on aspeed support at present,
>> but we're keeping an eye on it and are definitely excited to see
>> others contributing in that space!
> 
> Cedric,
> 
> I noticed you wrote the smbus_ipmi device in qemu. 

I wrote an experimental iBT device model using a chardev device backend 
to communicate with the external world (the host)

> It looks like this
> is meant to operate on the host-side using the SSIF driver.  

The goal was to connect a Aspeed BMC QEMU machine to a PowerNV QEMU machine 
using an external IPMI BMC. The PowerNV machine uses by default an internal
BMC simulator but it can be switched to an external one and connect to a 
remote BMC using the OpenIPMI's lanserv serial interface.

It operated on top of the iBT device only.

C.


> I'm looking at the Kudo BMC board which uses SSIF on the BMC side, and
> don't see an SSIF driver yet in openbmc/ilnux, but I wanted to
> validate that the host-side of the equation is what you've provided in
> Qemu?  Perhaps a silly question, but I've been caught off guard by
> some bad assumptions recently. :)
> 
> Thanks,
> Patrick
> 
>>
>>>
>>> Cheers,
>>>
>>> C.
>>
>> - Patrick