From: Avi Kivity <avi@redhat.com>
To: John Baboval <john.baboval@virtualcomputer.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] New Memory API Question
Date: Thu, 27 Oct 2011 12:23:54 +0200 [thread overview]
Message-ID: <4EA9313A.9060104@redhat.com> (raw)
In-Reply-To: <4EA81094.5050400@virtualcomputer.com>
On 10/26/2011 03:52 PM, John Baboval wrote:
> Sorry for coming late to the party on this... I only read qemu-devel
> through a filter so I missed all the discussions on the new memory
> API. I have a question as to how it works and how it's supposed to
> work in certain scenarios.
>
> It's a question of flow. I'm following the code path through the
> creation of a new memory subregion. If I'm reading this properly, it
> would seem that a MemoryRegion - for example the ones used by VGA - go
> through the following flow:
>
> memory_region_init_ram() - (mr->destructor is set to
> memory_region_destructor_ram)
> memory_region_add_subregion(system_memory, ...) ->
> memory_region_update_topology() ->
> address_space_update_topology()
> address_space_update_topology_part()
> as_memory_range_add() - through the ops vector
> memory_region_prepare_ram_addr()
>
>
> At this point it seems that the destructor is overwritten with the
> memory_region_destructor_iomem(), and it loses track of the proper way
> to ever free the memory region. Is this correct, or am I missing
> something?
It's correct; this is a bug.
>
> Or does it not matter because nobody ever calls memory_region_destroy
> for system memory regions?
It can still happen via hotunplug of an ivshmem device, or memory
hotunplug (when it is eventually implemented).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
prev parent reply other threads:[~2011-10-27 10:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-26 13:52 [Qemu-devel] New Memory API Question John Baboval
2011-10-26 17:54 ` John Baboval
2011-10-30 11:54 ` Avi Kivity
2011-10-27 10:23 ` Avi Kivity [this message]
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