Re: [Qemu-discuss] Qemu-system-sparc: What would I need to change to add functionality to save the nvram content between boots ?

[Jim Jarvie]

Hi Max,

What options do you need ?

Using :

-net nic,macaddr=00:80:<fill in MAC of the Sparc box> -M SS-20 (for a SPARC-20)

Will get the host ID to match whatever your original SPARC box had and that will satisfy lmgrd.

If you need SCSI IDs properly set (e.g. disk and CD to correct place), normally disks are SCSI ID 3 [on my systems] and you set that with

-drive file=xxxxx,format=raw,unit=3

With that, the default NVRAM boot options should boot the disk when you enter boot.

For a CDROM, from recollection, it defaults to unit=2 (don't have a machine to verify this right now but if you run boot cdrom and check for the ID it's looking for and match that).

That should be all you normally need to match the NVRAM defaults (except for auto-boot).

Now, some old info I could find suggests :

-prom-env 'boot-device=disk1' -prom-env 'auto-boot?=true'

(change disk1 to whatever you set up)

Will do that.  I've not been able to verify this is still true though as there were comments about it being broken (anyone else want to jump in?)

However, if it does not, you can script booting by starting the QEMU process with serial console over TCP and then send a boot command to it using an expect script.  The example link I sent you before has the process started with a serial console over TCP, which should give you a starting point.

Jim

On 10/09/2015 8:58 AM, Maximilian H. wrote:

Hello,

I was looking into what parts would need change to save and restore the
nvram content for the qemu-system-sparc vm between boots.

I see the code in hw/timer/m48t59.c that implements the nvram.

So some questions arise, and before I spend too much time poking around
the still unknown code, I'd thought I ask first.

1. Command line processing starts in vl.c in the main fct there ? Can I
add a command line argument there, say "-sparcnvram" ?

2. In hw/timer/m48t59.c has no functionality that I see from having a
look at it (not in depth) to save or restore the nvram's contents for
sparc. Is there a general facility that qemu has that provides such a
functionality - i.e. is there a general qemu save and restore framework ?

3. Is there an example somebody could point me to that implements
something similar ? Imitation is the sincerest of flattery ....

4. All the alarm and watchdog functionality that the m48t08 provides, is
that used on sparc too ?

5. Besides what is in
http://wiki.qemu.org/Documentation/GettingStartedDevelopers, is there
some qemu coding documentation to make it faster for somebody unfamilar
with qemu's code like me to be able to implement something ? I'd like to
spend a few evenings on this, produce a patch and move on.

Thanks
BR
Max.

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