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From: Ian Jackson <Ian.Jackson@eu.citrix.com>
To: George Dunlap <george.dunlap@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
	Roger Pau Monne <roger.pau@citrix.com>,
	Wei Liu <wei.liu2@citrix.com>,
Subject: Re: [PATCH 6/8] libxl: Allow local access for block devices with hotplug scripts
Date: Thu, 17 Mar 2016 18:36:29 +0000	[thread overview]
Message-ID: <22250.63789.160895.300725@mariner.uk.xensource.com> (raw)
In-Reply-To: <1458144557-29070-7-git-send-email-george.dunlap@citrix.com>

George Dunlap writes ("[PATCH 6/8] libxl: Allow local access for block devices with hotplug scripts"):
> pygrub and qemuu need to be able to access a VM's disks locally in
> order to be able to pull out the kernel and provide emulated disk
> access, respectively.  This can be done either by accessing the local
> disk directly, or by plugging the target disk into dom0 to allow
> access.

Some long lines, `if(', etc., in this patch, I'm afraid.

> Unfortunately, while the plugging machinery works for pygrub, it does
> not yet work for qemuu; meaning that disk hotplug scripts cannot be
> used with HVM domains.
> Fortunately, disks using hotplug scripts created in dom0 do create a
> block device as part of set-up, which can be accessed locally; and if
> they use block-common.sh:write_dev, this path will bre written to
> physical-device-path.
> Modify libxl__device_disk_setdefault() to be able to fish this path
> out of xenstore and pass it back.
> We need the target domid to find the appropriate xenstore node, so add
> that to libxl__disk_local_state.

I couldn't find that change in this patch.

> +    /* 
> +     * If the format isn't raw and / or we're using a script, then see
> +     * if the script has written a path to the "cooked" node
> +     */
> +    if(disk->script && domid != INVALID_DOMID) {
> +        libxl__device device;
> +        char *be_path, *pdpath;
> +        int rc;

I don't see where you check that the disk is not being provided by a
driver domain - in which case the hotplug script ran in the driver
domain and the device path is also only in the driver domain.

(By `driver domain' I mean, really, a domain other than this one.)

>  _hidden char * libxl__device_disk_find_local_path(libxl__gc *gc, 
> +                                                  libxl_domid domid,

This new parameter would maybe be a little less confusing if it were
explicitly `guest_domid'; after all it might be the driver domain


Xen-devel mailing list

  reply	other threads:[~2016-03-17 18:36 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16 16:09 [PATCH 0/8] tools: Allow HVM domains emulated access to disks provided by hotplug scripts George Dunlap
2016-03-16 16:09 ` [PATCH 1/8] tools/hotplug: Add a "dummy" hotplug script for testing George Dunlap
2016-03-16 16:54   ` Ian Jackson
2016-03-16 16:09 ` [PATCH 2/8] libxl: Remove redundant setting of phyical-device George Dunlap
2016-03-16 16:54   ` Ian Jackson
2016-03-16 16:09 ` [PATCH 3/8] tools/hotplug: Write physical-device-path in addition to physical-device George Dunlap
2016-03-16 16:56   ` Ian Jackson
2016-03-16 16:57     ` George Dunlap
2016-03-16 16:09 ` [PATCH 4/8] libxl: Move check for local access to a funciton George Dunlap
2016-03-16 16:58   ` Ian Jackson
2016-03-16 17:02     ` George Dunlap
2016-03-17 18:11   ` Ian Jackson
2016-03-21 15:35     ` George Dunlap
2016-03-16 16:09 ` [PATCH 5/8] libxl: Share logic for finding path between qemuu and pygrub George Dunlap
2016-03-17 18:22   ` Ian Jackson
2016-03-18 17:09     ` George Dunlap
2016-04-01 14:17       ` Ian Jackson
2016-03-16 16:09 ` [PATCH 6/8] libxl: Allow local access for block devices with hotplug scripts George Dunlap
2016-03-17 18:36   ` Ian Jackson [this message]
2016-03-18 17:17     ` George Dunlap
2016-03-16 16:09 ` [PATCH 7/8] docs: Document block-script protocol George Dunlap
2016-03-16 22:57   ` Jim Fehlig
2016-03-17  9:55     ` George Dunlap
2016-03-17 18:38   ` Ian Jackson
2016-03-16 16:09 ` [PATCH 8/8] DO NOT APPLY libxl: Change hotplug script interface to use physical-device-path George Dunlap

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