Re: [libvirt] [PATCH 6/8] Add unique_id to nodedev output

On 06/11/2014 05:31 AM, Daniel P. Berrange wrote: > On Tue, Jun 10, 2014 at 03:03:55PM -0400, John Ferlan wrote: >> Add an optional unique_id parameter to nodedev. Allows for easier lookup >> and display of the unique_id value in order to document for use with >> scsi_host code. >> >> Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; >> --- >> docs/formatnode.html.in | 11 +++++++++++ >> docs/schemas/nodedev.rng | 6 ++++++ >> src/conf/node_device_conf.c | 23 ++++++++++++++++------ >> src/conf/node_device_conf.h | 1 + >> src/node_device/node_device_linux_sysfs.c | 6 ++++++ >> src/test/test_driver.c | 5 +++-- >> .../pci_8086_27c5_scsi_host_0_unique_id.xml | 8 ++++++++ >> tests/nodedevxml2xmltest.c | 1 + >> 8 files changed, 53 insertions(+), 8 deletions(-) >> create mode 100644 tests/nodedevschemadata/pci_8086_27c5_scsi_host_0_unique_id.xml >> >> diff --git a/docs/formatnode.html.in b/docs/formatnode.html.in >> index 76bf8af..cdf0277 100644 >> --- a/docs/formatnode.html.in >> +++ b/docs/formatnode.html.in >> @@ -173,6 +173,17 @@ >> <dl> >> <dt><code>host</code></dt> >> <dd>The SCSI host number.</dd> >> + <dt><code>unique_id</code></dt> >> + <dd>On input, this optionally provides the value from the >> + 'unique_id' file found in the scsi_host's directory. To >> + view the values of all 'unique_id' files, use <code>find -H >> + /sys/class/scsi_host/host{0..9}/unique_id | >> + xargs grep '[0-9]'</code>. On output, if the unique_id >> + file exists, the value from the file will be displayed. >> + This can be used in order to help uniquely identify the >> + scsi_host adapter in a <a href="formatstorage.html"> >> + Storage Pool</a>. <span class="since">Since 1.2.6</span> >> + </dd> > > Where is the data from the 'unique_id' coming from ? Is this since that > Linux makes up, or is it some standard attribute from the hardware ? It > would be desirable to document what it is in a way that's not simply > refering to Linux sysfs, since sysfs itself is mostly undocumented :-) > > Using 'unique_id' was from Osier's initial design - I 'assumed' that his research into this had determined using this was unique enough. A small amount of searching turns this up: https://lkml.org/lkml/2011/8/17/274 ... +What: /sys/bus/scsi/devices/host*/scsi_host/host*/unique_id +Date: February, 2003 +KernelVersion: Unknown +Contact: James Bottomley <James.Bottomley(a)HansenPartnership.com&gt; +Description: + Read only unsigned integer uniquely identifying the SCSI host + within the system. This value is assigned by the low level + driver. + ... Also from various sources, there's '/linux/include/scsi/scsi_host.h /* * This is a unique identifier that must be assigned so that we * have some way of identifying each detected host adapter properly * and uniquely. For hosts that do not support more than one card * in the system at one time, this does not need to be set. It is * initialized to 0 in scsi_register. */ unsigned int unique_id;