Re: [Xen-devel] can't boot from iso on cifs mount

[Vasiliy Tolstov <v.tolstov@xxxxxxxxx>]

Failed again.
may be in xenstore.c in this code i need to delete O_DIRECT flag?

In strace before i get messages about fallback without O_DIRECT
(provided with patch) i get this:

write(2, "Using file /var/storage/iso/SW_D"..., 130) = 130
open("/var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Russian_w_SP1_MLF_X17-22616_vase.iso",
O_RDONLY|O_DIRECT) = -1 EINVAL (Invalid argument)
write(2, "qemu: could not open vbd '/local"..., 216) = 216

My be in this code i append fallback?

            if (bdrv_open2(bs, params, flags|BDRV_O_CACHE_WB /*
snapshot and write-back */, format) < 0) {
                fprintf(stderr, "qemu: could not open vbd '%s' or hard
disk image '%s' (drv '%s' format '%s')\n", buf, params, drv ? drv :
"?", format ? format->format_name : "0");
            } else {
                char* snapshot = get_snapshot_name(atoi(e_danger[i]));
                if (snapshot) {
                    fprintf(stderr, "Using snapshot %s\n", snapshot);
                    ret = bdrv_snapshot_goto(bs, snapshot);
                    switch (ret) {
                    case 0:
                        /* Success */
                        break;
                    case -ENOTSUP:
                        /* Don't abort here (could be read-only ISO) */
                        fprintf(stderr, "Snapshots are not supported for "
                            "this image file format\n");
                        break;
                    case -ENOENT:
                        fprintf(stderr, "No such snapshot, skipping this "
                            "image file\n");
                        continue;
                    default:
                        fprintf(stderr, "Could not load snapshot, skipping"
                            " this image file\n");
                        continue;
                    }
                }
            }

2013/1/30 Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>:
> Sorry that was my stupid mistake.
> This should work:
>
> diff --git a/hw/xen_disk.c b/hw/xen_disk.c
> index 33a5531..1786db8 100644
> --- a/hw/xen_disk.c
> +++ b/hw/xen_disk.c
> @@ -659,9 +659,16 @@ static int blk_init(struct XenDevice *xendev)
>         if (blkdev->bs) {
>             if (bdrv_open2(blkdev->bs, blkdev->filename, qflags,
>                             bdrv_find_format(blkdev->fileproto)) != 0) {
> -               bdrv_delete(blkdev->bs);
> -               blkdev->bs = NULL;
> -           }
> +                /* try without O_DIRECT */
> +                xen_be_printf(&blkdev->xendev, 0, "opening %s with O_DIRECT 
> failed, trying write-through.\n",
> +                        blkdev->filename);
> +                qflags &= ~BDRV_O_NOCACHE;
> +                if (bdrv_open2(blkdev->bs, blkdev->filename, qflags,
> +                            bdrv_find_format(blkdev->fileproto)) != 0) {
> +                    bdrv_delete(blkdev->bs);
> +                    blkdev->bs = NULL;
> +                }
> +            }
>         }
>         if (!blkdev->bs)
>             return -1;
>
> On Wed, 30 Jan 2013, Vasiliy Tolstov wrote:
>> Strace shows that qemu after O_DIRECT next try with O_DIRECT
>> open("/var/storage/iso/winpe_amd64.iso", O_RDONLY|O_DIRECT) = -1
>> EINVAL (Invalid argument)
>> write(2, "xen be: qdisk-832: ", 19)     = 19
>> write(2, "xen be: qdisk-832: ", 19)     = 19
>> write(2, "opening /var/storage/iso/winpe_a"..., 85) = 85
>> write(2, "opening /var/storage/iso/winpe_a"..., 85) = 85
>> open("/var/storage/iso/winpe_amd64.iso", O_RDONLY|O_DIRECT) = -1
>> EINVAL (Invalid argument)
>>
>> 2013/1/30 Vasiliy Tolstov <v.tolstov@xxxxxxxxx>:
>> > Thanks for patch. But it not solve problem:
>> > Now i have :
>> > domid: 6
>> > Using file /dev/disk/vbd/21-828 in read-write mode
>> > Strip off blktap sub-type prefix to  (drv 'aio')
>> > Watching /local/domain/0/device-model/6/logdirty/cmd
>> > Watching /local/domain/0/device-model/6/command
>> > Watching /local/domain/6/cpu
>> > char device redirected to /dev/pts/5
>> > qemu_map_cache_init nr_buckets = 10000 size 4194304
>> > Could not open /var/run/tap/qemu-read-6
>> > shared page at pfn feffd
>> > buffered io page at pfn feffb
>> > Guest uuid = c98c33c8-1891-41ec-96a0-984f3df80def
>> > xen be: qdisk-5632: xen be: qdisk-5632: opening  with O_DIRECT failed,
>> > trying write-through.
>> > opening  with O_DIRECT failed, trying write-through.
>> > populating video RAM at ff000000
>> > mapping video RAM from ff000000
>> > Register xen platform.
>> > Done register platform.
>> > platform_fixed_ioport: changed ro/rw state of ROM memory area. now is rw 
>> > state.
>> > xs_read(/local/domain/0/device-model/6/xen_extended_power_mgmt): read error
>> > medium change watch on `hdc' (index: 1): aio:
>> > I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0
>> > Log-dirty: no command yet.
>> > I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0
>> > I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0
>> > vcpu-set: watch node error.
>> > I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0
>> > xs_read(/local/domain/6/log-throttling): read error
>> > qemu: ignoring not-understood drive `/local/domain/6/log-throttling'
>> > medium change watch on `/local/domain/6/log-throttling' - unknown
>> > device, ignored
>> > xen be: qdisk-5632: xen be: qdisk-5632: opening  with O_DIRECT failed,
>> > trying write-through.
>> > opening  with O_DIRECT failed, trying write-through.
>> > log_throttling disabled
>> > qemu: ignoring not-understood drive `/local/domain/6/log-throttling'
>> > medium change watch on `/local/domain/6/log-throttling' - unknown
>> > device, ignored
>> > vga s->lfb_addr = f0000000 s->lfb_end = f1000000
>> > platform_fixed_ioport: changed ro/rw state of ROM memory area. now is rw 
>> > state.
>> > platform_fixed_ioport: changed ro/rw state of ROM memory area. now is ro 
>> > state.
>> >
>> >
>> > (XEN) HVM6: VGABios $Id: vgabios.c,v 1.67 2008/01/27 09:44:12 vruppert Exp 
>> > $
>> > (XEN) HVM6: VBE Bios $Id: vbe.c,v 1.60 2008/03/02 07:47:21 vruppert Exp $
>> > (XEN) HVM6: Bochs BIOS - build: 06/23/99
>> > (XEN) HVM6: $Revision: 1.221 $ $Date: 2008/12/07 17:32:29 $
>> > (XEN) HVM6: Options: apmbios pcibios eltorito PMM
>> > (XEN) HVM6:
>> > (XEN) HVM6: ata0-0: PCHS=16383/16/63 translation=lba LCHS=1024/255/63
>> > (XEN) HVM6: ata0 master: QEMU HARDDISK ATA-7 Hard-Disk (10246 MBytes)
>> > (XEN) HVM6: IDE time out
>> > (XEN) HVM6: ata1 master: QEMU DVD-ROM ATAPI-4 CD-Rom/DVD-Rom
>> > (XEN) HVM6: IDE time out
>> > (XEN) HVM6:
>> > (XEN) HVM6:
>> > (XEN) HVM6:
>> > (XEN) HVM6: Press F12 for boot menu.
>> > (XEN) HVM6:
>> > (XEN) HVM6: Booting from Hard Disk...
>> > (XEN) HVM6: Boot from Hard Disk failed: not a bootable disk
>> > (XEN) HVM6:
>> > (XEN) HVM6:
>> > (XEN) HVM6: No bootable device.
>> > (XEN) HVM6: Powering off in 30 seconds.
>> > (XEN) hvm.c:1080:d6 All CPUs offline -- powering off.
>> >
>> > 2013/1/22 Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>:
>> >> On Tue, 22 Jan 2013, Ian Campbell wrote:
>> >>> Please don't top post.
>> >>>
>> >>> On Tue, 2013-01-22 at 05:38 +0000, Vasiliy Tolstov wrote:
>> >>> > Thanks!
>> >>> > I found, that now xl tries to open iso with O_DIRECT flag.
>> >>> > open("/var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Russian_w_SP1_MLF_X17-22616_vase.iso",
>> >>> > O_RDONLY|O_DIRECT) = -1 EINVAL (Invalid argument)
>> >>> > write(2, "qemu: could not open vbd '/local"..., 217) = 217
>> >>
>> >> xl? I guess you mean QEMU tries to open the ISO with O_DIRECT.
>> >>
>> >>
>> >>> I guess CIFS doesn't support O_DIRECT. It looks like it does have mount
>> >>> -o directio though, worth a try.
>> >>>
>> >>> I'm not sure what options exist to turn this off from the qemu side --
>> >>> Stefano? I also have a feeling something changed in this regard in 4.2.x
>> >>
>> >> Given that you are not passing any device_model_version option to xl, I
>> >> assume that you are running qemu-xen-traditional (ps should show that a
>> >> binary called qemu-dm is running).
>> >>
>> >> If that is the case, there is currently no way to specify any flags.
>> >> However the interesting bit is that qemu-xen-traditional opens files
>> >> corresponding to emulated devices with BDRV_O_CACHE_WB and opens files
>> >> corresponding to PV interfaces using BDRV_O_NOCACHE (this means
>> >> O_DIRECT).
>> >> This means that the failure should be caused by hw/xen_disk.c trying to
>> >> opening the iso O_DIRECT. Paradoxically the PV inteface for a cdrom
>> >> drive is usually never used AFAIK.
>> >>
>> >> Did the Windows PV drivers start using the PV cdrom interface all of a
>> >> sudden?
>> >>
>> >> In any case I think that the best thing we could do it fall back to
>> >> write-through (or should it be write-back? It might not be safe..) in
>> >> case O_DIRECT fails. This is what qemu-xen does in such cases.
>> >>
>> >> Try this patch:
>> >>
>> >> ---
>> >>
>> >> diff --git a/hw/xen_disk.c b/hw/xen_disk.c
>> >> index 33a5531..d6d71fe 100644
>> >> --- a/hw/xen_disk.c
>> >> +++ b/hw/xen_disk.c
>> >> @@ -659,9 +659,16 @@ static int blk_init(struct XenDevice *xendev)
>> >>         if (blkdev->bs) {
>> >>             if (bdrv_open2(blkdev->bs, blkdev->filename, qflags,
>> >>                             bdrv_find_format(blkdev->fileproto)) != 0) {
>> >> -               bdrv_delete(blkdev->bs);
>> >> -               blkdev->bs = NULL;
>> >> -           }
>> >> +                /* try without O_DIRECT */
>> >> +                xen_be_printf(&blkdev->xendev, 0, "opening %s with 
>> >> O_DIRECT failed, trying write-through.\n",
>> >> +                        blkdev->filename);
>> >> +                qflags &= BDRV_O_NOCACHE;
>> >> +                if (bdrv_open2(blkdev->bs, blkdev->filename, qflags,
>> >> +                            bdrv_find_format(blkdev->fileproto)) != 0) {
>> >> +                    bdrv_delete(blkdev->bs);
>> >> +                    blkdev->bs = NULL;
>> >> +                }
>> >> +            }
>> >>         }
>> >>         if (!blkdev->bs)
>> >>             return -1;
>> >>
>> >
>> >
>> >
>> > --
>> > Vasiliy Tolstov,
>> > Clodo.ru
>> > e-mail: v.tolstov@xxxxxxxxx
>> > jabber: vase@xxxxxxxxx
>>
>>
>>
>> --
>> Vasiliy Tolstov,
>> Clodo.ru
>> e-mail: v.tolstov@xxxxxxxxx
>> jabber: vase@xxxxxxxxx
>>



-- 
Vasiliy Tolstov,
Clodo.ru
e-mail: v.tolstov@xxxxxxxxx
jabber: vase@xxxxxxxxx

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