Re: [Qemu-devel] KVM call agenda for tuesday 31

[Mitsyanko Igor <i.mitsyanko@samsung.com>]

On 01/31/2012 05:15 PM, Andreas Färber wrote:
> Am 31.01.2012 00:53, schrieb Anthony Liguori:
>> On 01/30/2012 05:41 PM, Andreas Färber wrote:
>>> Am 30.01.2012 19:55, schrieb Juan Quintela:
>>>> Please send in any agenda items you are interested in covering.
>
>>> VMState:
>>> Anthony specifically said that VMState were not affected by QOM and that
>>> patches should not be deferred until the merge. Yet there's no review
>>> and/or decision-making for a month now. Ping^2 for AHCI+SDHC.
>>
>> Do you have pointers (to pending VMState patches)?
>
> http://patchwork.ozlabs.org/patch/137732/ (PATCH v4)
>
> It's basically about how to deal with variable-sized arrays. (Alex
> mentioned it on one call around November.) I found ways to deal with
> subsets of arrays embedded within the struct and variable-sized list of
> pointers to structs but no solution for a malloc()'ed array of structs.
> Maybe I'm just too stupid to see. Anyway, no one commented since Xmas.
>
> Igor posted (and refined for v2) a patch with a callback-based approach
> that I find promising. From my view, unofficially Juan is the VMState
> guy, he's been cc'ed. Are we lacking an official maintainer that cares?
> Or is Juan the official, undocumented maintainer but simply busy?
>
> SUSE's interest is making AHCI migratable, and my VMState workaround for
> that is simply ugly:
>
> http://patchwork.ozlabs.org/patch/133066/ (RFC)
>

If I'm not mistaken, if you change AHCIState's ".ports" type to uint32_t 
you can use existing VMSTATE_BUFFER_MULTIPLY macro like this:

VMSTATE_BUFFER_MULTIPLY(dev, AHCIState, 0, NULL, 0, ports, 
sizeof(AHCIDevice))

VMSTATE_BUFFER_MULTIPLY currently lacks VMS_POINTER flag and therefore 
doesn't make any use of _start field (you don't need it anyway)

Nevertheless, VMSTATE_BUFFER_MULTIPLY is just a partial solution to a 
bigger set of possible problems. SD card's vmstate implementation 
requires shift operation, SDHC gets size from switch {} statement, 
something else later may require division or addition e.t.c., 
get_bufsize callback will cover all possible cases.



-- 
Mitsyanko Igor
ASWG, Moscow R&D center, Samsung Electronics
email: i.mitsyanko@samsung.com