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Re: [Xen-devel] [PATCH] qemu-xen-3.4-testing: Fix read-only image file h

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "'xen-devel@xxxxxxxxxxxxxxxxxxx'" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] qemu-xen-3.4-testing: Fix read-only image file handling
From: Michal Novotny <minovotn@xxxxxxxxxx>
Date: Fri, 04 Jun 2010 15:45:53 +0200
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On 06/04/2010 03:16 PM, Keir Fraser wrote:
On 04/06/2010 14:13, "Michal Novotny"<minovotn@xxxxxxxxxx>  wrote:

Keir,
I tried it and it's already up to date:

$ git pull -a
Already up-to-date. Yeeah!
$
Don't believe you, or it's not the one that's actually being built. :-) If
you grep in the tree for xc_interface_open() you should see it is correctly
passing three args now.

Sorry, my bad, something was wrong with my git tree so I deleted it and pulled again.

Thanks,
Michal

And if it is, then that will build okay. If it's not
passing three args, the tree is stale.

  -- Keir

-- Michal

On 06/04/2010 03:11 PM, Keir Fraser wrote:
You need to bring your qemu repo up to date. Throw it away, or go into it
and 'git pull -a'.

   -- Keir

On 04/06/2010 14:00, "Michal Novotny"<minovotn@xxxxxxxxxx>   wrote:


Well, now the kernel is booting but when I'm trying to recompile tools
and stubdom images it's not OK returning those errors:

...
qemu successfuly configured for Xen qemu-dm build
make -C ioemu-dir install
=== PCI passthrough capability has been enabled ===
make[3]: Entering directory
`/home2/shared/xen-unstable.hg/tools/ioemu-remote'
=== PCI passthrough capability has been enabled ===
=== PCI passthrough capability has been enabled ===
make[4]: Entering directory
`/home2/shared/xen-unstable.hg/tools/ioemu-remote/i386-dm'
CC i386-dm/vl.o
/home2/shared/xen-unstable.hg/tools/ioemu-dir/vl.c: In function Œmain¹:
/home2/shared/xen-unstable.hg/tools/ioemu-dir/vl.c:5729: warning:
implicit declaration of function Œdma_helper_init¹
/home2/shared/xen-unstable.hg/tools/ioemu-dir/vl.c:5731: error: too few
arguments to function Œxc_interface_open¹
make[4]: *** [vl.o] Error 1
make[4]: Leaving directory
`/home2/shared/xen-unstable.hg/tools/ioemu-remote/i386-dm'
make[3]: *** [subdir-i386-dm] Error 2
make[3]: Leaving directory
`/home2/shared/xen-unstable.hg/tools/ioemu-remote'
make[2]: *** [subdir-install-ioemu-dir] Error 2
make[2]: Leaving directory `/home2/shared/xen-unstable.hg/tools'
make[1]: *** [subdirs-install] Error 2
make[1]: Leaving directory `/home2/shared/xen-unstable.hg/tools'
make: *** [install-tools] Error 2
#

The command I used for compilation is `make install-xen&&   make
install-tools&&   make install-stubdom&&   make install-docs` on the
latest updated xen-unstable staging mercurial tree so I need to
investigate this further. Nevertheless, the dom0 2.6.31.13 is booting on
RHEL-5 which is good. That links you gave me Pasi helped, thanks! Now I
need to resolve those tools issues.

Michal

On 06/04/2010 12:57 PM, Michal Novotny wrote:

On 06/04/2010 12:42 PM, Pasi Kärkkäinen wrote:

On Fri, Jun 04, 2010 at 11:37:51AM +0200, Michal Novotny wrote:

Oh, one more thing I've discovered now. Since the codebase for
qemu-xen-unstable is looking the same like for qemu-xen-3.4-testing and
the patch is applicable without any modifications it could be working
for xen-4.1 unstable as well, unfortunately I was not able to boot
PVOPS
kernel since it always ends up in kernel panic, maybe the missing
drivers or something like that.


What kernel version? Did you use xen/stable-2.6.32.x branch from
xen.git?

It's the one that's being automatically downloaded from git as
linux-2.6-pvops.git. The URL is
git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git with the
"fetch" being set to "+refs/heads/*:refs/remotes/xen/*". This is the
.git/config automatically created by `make world` in xen-unstable tree:

[core]
repositoryformatversion = 0
filemode = true
bare = false
logallrefupdates = true
[remote "xen"]
url = git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git
fetch = +refs/heads/*:refs/remotes/xen/*
[branch "xen/stable-2.6.31.x"]
remote = xen
merge = refs/heads/xen/stable-2.6.31.x

By default it's using uhci-hcd/ehci-hcd and ohci-hcd as builtins but I
needed to change it to be modules since otherwise it's being stuck.
I'm trying this on RHEL-5 dom0 (I'm having second partition RHEL-5
with upstream xen).

See my example .config files from:
http://wiki.xensource.com/xenwiki/XenParavirtOps in the
"troubleshooting" section.

I'll have a look, thanks for the link.


Works on F12/F13 dom0's.

For el5 dom0 you might need these:
http://wiki.xensource.com/xenwiki/2.6.18-to-2.6.31-and-higher

Oh, ok, this may be very useful since I'm trying this on RHEL-5. Thanks!


aka
CONFIG_SYSFS_DEPRECATED=y
CONFIG_SYSFS_DEPRECATED_V2=y

Also atm I think you need CONFIG_XEN_XENBUS_FRONTEND=y in the .config
because of the recently added pv-on-hvm drivers (you'll get build
failure without that option),
so you need XEN_PCIDEV_FRONTEND XEN_BLKDEV_FRONTEND or
XEN_NETDEV_FRONTEND or XEN_FBDEV_FRONTEND needs to be =y.


Great! Thanks for your help Pasi! If anything I'll let you know.

Michal


-- Pasi



On 06/03/2010 04:12 PM, Michal Novotny wrote:

Oh, just one more thing that should be mentioned:

When you want to mount an image that is set as read-only in the domain
configuration file but you omit to set mode to read-only it results
into I/O errors when processing the requests. Remounting as read-only
or unmounting and remounting using the `mount /dev/* /path/to/mount -o
ro` shall do the mounting the correct way, i.e. with no I/O errors, so
make sure you mount those disks as read-only otherwise you can be
getting errors like:

end_request: I/O error, dev hdb, sector 52

Buffer I/O error on device hdb1, logical block 1

lost page write due to I/O error on hdb1


and for IDE devices you'll be getting several additional DeviceFault
errors since mounting the device read-write (default setting) writes
some data onto a disk at the mount-time.

Michal

On 06/03/2010 04:04 PM, Michal Novotny wrote:

[Well, I did send an e-mail to the list using git but it's not here
so I'm forwarding the e-mail to the list for sure:]

Hi,
this is the patch for qemu-xen-3.4-testing to fix the read-only
image file handling since the image file was always treated as
read-write which means that all the HVM guests were able to
write to all the disk images available in domain configuration
file no matter what the mode of the image was defined. This
patch fixes this functionality to honor the O_RDONLY in the
BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI
interfaces that uses it.

It's been tested on RHEL-5 with xen-3.4-testing version of
upstream xen with xen-3.4-testing qemu implementation.

For SCSI devices the DATA PROTECT request sense has been added
as found at: http://en.wikipedia.org/wiki/SCSI_Request_Sense_Command

file no matter what the mode of the image was defined. This
patch fixes this functionality to honor the O_RDONLY in the
BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI
interfaces that uses it.

It's been tested on RHEL-5 with xen-3.4-testing version of
Michal

Signed-off-by: Michal Novotny<minovotn@xxxxxxxxxx>


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--
Michal Novotny<minovotn@xxxxxxxxxx>, RHCE
Virtualization Team (xen userspace), Red Hat


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--
Michal Novotny<minovotn@xxxxxxxxxx>, RHCE
Virtualization Team (xen userspace), Red Hat


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