Re: [Qemu-devel] [PATCH 01/18] smbios: Add a function to directly add an entry

[Anthony Liguori <anthony@codemonkey.ws>]

Corey Minyard <cminyard@mvista.com> writes:

> On 07/30/2012 10:37 AM, Anthony Liguori wrote:
>> minyard@acm.org writes:
>>
>>> From: Corey Minyard <cminyard@mvista.com>
>>>
>>> There was no way to directly add a table entry to the SMBIOS table,
>>> even though the BIOS supports this.  So add a function to do this.
>>> This is in preparation for the IPMI handler adding it's SMBIOS table
>>> entry.
>>>
>>> Signed-off-by: Corey Minyard <cminyard@mvista.com>
>> I don't expect that hardware ever adds SMBIOS entries.  Rather, the BIOS
>> adds the entries by probing the hardware.
>
> Well, memory entries are added by QEMU, why not let the BIOS probe for 
> that?

QEMU doesn't add any entries by default.  SeaBIOS owns SMBIOS.  QEMU
uses a backchannel to hand SeaBIOS tables that SeaBIOS can then expose.
The reason we use a table based interface is because type 0 and type 1
tables can have vendor extensions that are in a vendor specific format.

But SeaBIOS unquestionably owns SMBIOS generation.

>  Plus, I really doubt that BIOSes on real systems probe for this.  
> I'd guess they are hard-coded.

I think you'd be surprised how little is hard coded on modern BIOSes.

>> So I think you should solve this in SeaBIOS, instead of trying to do it
>> in QEMU.  I think that also solves the problem you have with
>> pre-firmware init.
>
> The user can pass the I/O base and IRQ values in on the QEMU command 
> line, and they can be arbitrary values.  The BIOS is not going to be 
> able to probe for those.

Then pass the information that the BIOS needs through fw_cfg.  That's
what it's there for.

Regards,

Anthony Liguoi

>
> -corey