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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sat, 2013-01-19 at 11:23 +0000, Vasiliy Tolstov wrote:
> After switching from xm to xl

Which version of Xen?

>  i found that all my windows hvm domU
> can't boot from iso. domU can't boot is iso on cifs mount point. If
> that iso move from cifs to ramdisk - all work's fine.
> 
> cifs mount:
> //cc/public on /var/storage type cifs
> (rw,relatime,vers=1.0,sec=ntlm,cache=none,unc=\\cc\public,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.25.254,unix,posixpaths,serverino,acl,rsize=1048576,wsize=65536,actimeo=1)
> 
> xl messages contains:
> Using file /dev/disk/vbd/21-822 in read-write mode
> Strip off blktap sub-type prefix to
> /var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Russian_w_SP1_MLF_X17-22616_vase.iso
> (drv 'aio')
> Using file 
> /var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Russian_w_SP1_MLF_X17-22616_vase.iso
> in read-only mode
> qemu: could not open vbd '/local/domain/0/backend/qdisk/162/5632/mode'
> or hard disk image
> '/var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Ru
> ssian_w_SP1_MLF_X17-22616_vase.iso' (drv 'aio' format 'raw')
> 
> domain started with xl create /etc/empty \
> -d \
> name="21-10824" \
> kernel="/usr/lib/xen/boot/hvmloader" \
> builder="hvm" \
> memory=768 \
> vcpus=4 \
> vif=["mac=00:16:3e:00:1a:e4,ip=62.76.190.208,type=paravirtualised"]
> disk=["phy:/dev/disk/vbd/21-822,hda,w",
> "file:/var/storage/iso/SW_DVD5_Windows_Svr_DC_EE_SE_Web_2008_R2_64Bit_Russian_w_SP1_MLF_X17-22616_vase.iso,hdc:cdrom,r",
> "file:/var/storage/iso/winpe_amd64.iso,hdb,r,devtype=cdrom"] \

If you remove the first CD-ROM entry does the second one work? I expect
not (they both parse to the same sort of thing) and it is just failing
at the first and not even trying the second.

Can you read the .iso manually (e.g. using md5sum or od or something) as
root on the dom0? (I'm wondering if there is some CIFS equivalent of
root_squash)

Do you get anything in /var/log/xen/qemu-dm* in addition to the xl logs?

One approach to debugging this might be to use
        device_model_override="/path/to/my-qemu"
where my-qemu is a script which runs
        strace -o /tmp/qemu.strace -fff /usr/lib/xen/bin/qemu-dm $@

The strace might tell you a little bit more about how/why it is failing
to open the file.

Ian.


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