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Re: [Qemu-devel] [PATCH v2 0/8] acpi: make ROMs resizeable
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/8] acpi: make ROMs resizeable |
Date: |
Thu, 18 Dec 2014 20:16:26 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Michael S. Tsirkin (address@hidden) wrote:
> On Thu, Dec 18, 2014 at 06:49:09PM +0000, Dr. David Alan Gilbert wrote:
> > * Michael S. Tsirkin (address@hidden) wrote:
> > I'm generally happy with this set for what you're using it for,
> > except that I'd like some big hairy warnings in comments
> > near the resize functions to make it clear when it's safe
> > to do it.
>
> Really always: whenever resize callback updates all
> guest visible state.
The outgoing side worries me due to previous painful encounters
with arch_init.c's migration_dirty_pages. It's a counter that
knows exactly how many pages it has and it gets incremented/decremented
and *must* be right otherwise the migration never ends.
It's derived from used_pages in your world, so that would change.
That's just the one that comes to mind;
A comment saying 'Don't use during an outgoing migration'
would cover that - but I'm not that confident there aren't other uses
we have to be careful of.
> > What I don't really understand is how it would work for anything mapped
> > into guest address space, how that mapping would be updated.
> >
> > Dave
>
> That would be a job of the resize function: it can update kvm.
Yes I guess so, I'm just not sure what the guest is going to think about it.
Dave
>
> > >
> > > Michael S. Tsirkin (8):
> > > cpu: add cpu_physical_memory_clear_dirty_range_nocode
> > > memory: add memory_region_set_size
> > > exec: cpu_physical_memory_set/clear_dirty_range
> > > exec: split length -> used_length/max_length
> > > exec: qemu_ram_alloc_resizeable, qemu_ram_resize
> > > arch_init: support resizing on incoming migration
> > > memory: API to allocate resizeable RAM MR
> > > acpi-build: make ROMs RAM blocks resizeable
> > >
> > > hw/lm32/lm32_hwsetup.h | 3 +-
> > > include/exec/cpu-all.h | 12 +++--
> > > include/exec/memory.h | 34 +++++++++++++
> > > include/exec/ram_addr.h | 22 +++++++--
> > > include/hw/loader.h | 4 +-
> > > arch_init.c | 28 ++++++-----
> > > exec.c | 129
> > > +++++++++++++++++++++++++++++++++++++-----------
> > > hw/core/loader.c | 18 +++++--
> > > hw/i386/acpi-build.c | 19 +++++--
> > > memory.c | 33 +++++++++++++
> > > 10 files changed, 242 insertions(+), 60 deletions(-)
> > >
> > > --
> > > MST
> > >
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH v2 1/8] cpu: add cpu_physical_memory_clear_dirty_range_nocode, (continued)
- [Qemu-devel] [PATCH v2 1/8] cpu: add cpu_physical_memory_clear_dirty_range_nocode, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 2/8] memory: add memory_region_set_size, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 3/8] exec: cpu_physical_memory_set/clear_dirty_range, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 4/8] exec: split length -> used_length/max_length, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 5/8] exec: qemu_ram_alloc_resizeable, qemu_ram_resize, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 6/8] arch_init: support resizing on incoming migration, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 7/8] memory: API to allocate resizeable RAM MR, Michael S. Tsirkin, 2014/12/16
- [Qemu-devel] [PATCH v2 8/8] acpi-build: make ROMs RAM blocks resizeable, Michael S. Tsirkin, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 0/8] acpi: make ROMs resizeable, Dr. David Alan Gilbert, 2014/12/18