Re: [Qemu-devel] [PATCH 00/16 RFC v6] ACPI memory hotplug

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 24 Jul 2013 17:52:50 +0800
Hu Tao <hutao@cn.fujitsu.com> wrote:

> v6 doesn't work here, things are going fine until online hotplugged
> memory in guest.
> 
> steps:
> 
> 1. qemu cmd:
> 
>   ./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -m 512,maxmem=2G,slots=1 \
>   -hda /mnt/data/libvirt-images/hut-rhel6.3.img -L ../pc-bios-memhp/
> 
>   (bios is from MST's acpi tree)
> 
> 2. hot-plug a dimm:
> 
>   device_adddimm,id=d0,size=1G
> 
> 3. online hotplugged memory(in guest):
> 
>   echo 'onlone' > /sys/devices/system/memory/memory/32/state
> 
> then after several seconds the console prints error messages like:
> 
>   nommu_map_sg: overflow 107c15000+4096 of device mask ffffffff
>   ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
>   ata1.00: cmd ca/00:10:d0:0d:a4/00:00:00:00:00/e0 tag 0 dma 8192 out
>            res 50/00:00:08:09:e0/00:00:00:00:00/e0 Emask 0x40 (internal error)
>   ata1.00: configured for MWDMA2
>   ata1: EH complete
> 
>   (repeat)
> 
> and can't do any disk I/O.
Looks like a guest bug where it tries to use high memory but assumes low one.
if you boot guest with initial memory 4Gb then it wont hit issue or use FC18
which doesn't have this problem.



>