Gonglei (Arei)
2013-May-24 02:59 UTC
Re: [Qemu-devel] use O_DIRECT to open disk images for IDE failed under xen-4.1.2 and qemu upstream
Hi,> > On Thu, 23 May 2013, Gonglei (Arei) wrote: > > Hi, all > > > > I use O_DIRECT to open disk images for IDE, but I'm failed. After debug, I get > the below logs: > > [2013-05-22 23:25:46] ide: CMD=c8 > > [2013-05-22 23:25:46] bmdma: readb 0x00 : 0x08 > > [2013-05-22 23:25:46] bmdma: writeb 0x00 : 0x09 > > [2013-05-22 23:25:46] bmdma_cmd_writeb: 0x00000009 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:25:46] bmdma: readb 0x02 : 0x01 > > [2013-05-22 23:26:39] bmdma: writeb 0x00 : 0x08 > > [2013-05-22 23:26:39] bmdma_cmd_writeb: 0x00000008 > > [2013-05-22 23:26:56] ====== offset:0 buf:0x7ff100f21c00 count:512 > aio_offset:0 > > [2013-05-22 23:31:30] ====== offset:0 buf:0x7ff100f21c00 count:512 > aio_offset:0 > > [2013-05-22 23:31:30] ====== handle_aiocb_rw_linear errno: -14 > > [2013-05-22 23:31:30] ====== paio_complete errno=14 > > [2013-05-22 23:31:30] ====== ide_dma_error!!! > > [2013-05-22 23:31:30] ide: read status addr=0x3f6 val=41 > > > > QEMU command line : > > qemu-system-i386 -xen-domid 837 -chardev > socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-837,server,nowait -mon > chardev=libxl-cmd,mode=control -name suse11 -vnc 0.0.0.0:1 -serial pty -boot > order=c -usb -usbdevice tablet -smp 2,maxcpus=2 -device > rtl8139,id=nic0,netdev=net0,mac=00:16:3e:13:d3:72 -netdev > type=tap,id=net0,ifname=tap837.0,downscript=no -M xenfv -m 2040 -drive > file=/mnt/sdd/image/suse.image,if=ide,index=0,media=disk,format=raw,cache > =none > > > > errno 14 shows Bad Address. And I find QEMU_AIO_MISALIGNED flag bit is > not set through debug. > > > > /* > > * If O_DIRECT is used the buffer needs to be aligned on a sector > > * boundary. Check if this is the case or tell the low-level > > * driver that it needs to copy the buffer. > > */ > > if ((bs->open_flags & BDRV_O_NOCACHE)) { > > if (!bdrv_qiov_is_aligned(bs, qiov)) { //if the address is > aligned-512, will no meet the conditions > > type |= QEMU_AIO_MISALIGNED; > > #ifdef CONFIG_LINUX_AIO > > } else if (s->use_aio) { > > return laio_submit(bs, s->aio_ctx, s->fd, sector_num, qiov, > > nb_sectors, cb, opaque, type); > > #endif > > > > Next process: > > static ssize_t handle_aiocb_rw(struct qemu_paiocb *aiocb) > > { > > ssize_t nbytes; > > char *buf; > > > > if (!(aiocb->aio_type & QEMU_AIO_MISALIGNED)) { > > /* > > * If there is just a single buffer, and it is properly aligned > > * we can just use plain pread/pwrite without any problems. > > */ > > if (aiocb->aio_niov == 1) > > return handle_aiocb_rw_linear(aiocb, > aiocb->aio_iov->iov_base); //this way, and reports errno 14 next > > > > Anyone have a good method to resolve this bug? Thanks! > > I know that this is not the answer you are looking for but why do you > want to use O_DIRECT with IDE? > It should be perfectly safe to use write-back.A few days ago, I asked a question about the IDE FLUSH time of guest： http://lists.nongnu.org/archive/html/qemu-devel/2013-05/msg02642.html finally I found that because Qemu use write-back flag to open disk images by default. so I hope to use O_DIRECT to avoid meeting that problem, but I'm failed under Xen platform with Qemu upstream. -Gonglei _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel