Hi paolo, With -M pc,trim works well in windows guest with ide device and ahci bus.
About the filter driver,you mean do something in windows virtio-scsi driver,let it send unmap command to qemu? Thanks baiqing. > -----Original Message----- > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > Sent: Wednesday, July 24, 2013 2:46 PM > To: Libaiqing > Cc: qemu-devel@nongnu.org > Subject: Re: trim in windows guest witch virtio > > Il 24/07/2013 02:53, Libaiqing ha scritto: > > Hi paolo, > > > > I test window guest with ide device with the following config,trim > with ide drive failed. > > > > 1 The host fs is ext4 with discard option: > > /dev/sdb1 on /home/sdb type ext4 > (rw,relatime,discard,data=ordered) > > > > 2 qemu config : ide drive with discard open > > x86_64-softmmu/qemu-system-x86_64 -enable-kvm -name win7 -M > pc-0.15 -m 1024 -smp 2 -boot c -device > piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive > file=/home/win7_base.qcow2,if=ide,index=0,format=qcow2,id=ad -drive > file=/home/sdb/raw.img,if=ide,index=1,format=raw,id=hd,discard=on > -monitor stdio -vga qxl -vnc :1 -device usb-tablet,id=input0 > > TRIM is supported only on "-M pc-1.5" and "-M pc". > > > 3 In win7 guest,init drive d,fill it with files,then shift+del files > > > > 4 The file /home/sdb/raw.img does not become small,when listing > with -s option. > > > > It seems that the windows ntfs does not send trim to ide controller. > No IDE_DMA_TRIM request received. > > Note that this may not happen immediately. NTFS may send TRIM later. > > > Is there any config wrong? > > > > Btw,I found the info from the URL: > http://msdn.microsoft.com/en-us/library/windows/desktop/hh848053(v=vs. > 85).aspx > > Qemu can do the same thing like hyper-v with windows guest? > > I don't know, I never tested it with Windows guests. It looks like > Windows 8 would not need a filter driver to do TRIM on SCSI disks (you > could try with megasas, so that you do not need a driver for the HBA). > > Paolo