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dot '.' not allowed in xenstore key?

Motohiro Kanda




When I include dot '.' in xenstore key, the entry I have created gets removed when VM starts.

Is dot character not allowed in xenstore key? Any restrictions on character sets used in xenstore key?


How to reproduce:

This is the initial value.
$ xe vm-param-get uuid=snip param-name=xenstore-data
vm-data: ; vm-data/mmio-hole-size: 268435456


Add foo and aaa-bbb entries.

$ xe vm-param-set uuid=snip xenstore-data:vm-data/foo=bar
$ xe vm-param-set uuid=snip xenstore-data:vm-data/aaa-bbb=ccc

$ xe vm-param-get uuid=snip param-name=xenstore-data
vm-data/aaa-bbb: ccc; vm-data/foo: bar; vm-data: ; vm-data/mmio-hole-size: 268435456


Boot VM and see they are there. Good.

# xenstore list vm-data

# xenstore read vm-data/aaa-bbb


Shutdown the VM.

Now add a key ddd.eee
$ xe vm-param-set uuid=snip xenstore-data:vm-data/ddd.eee=fff


Looks good.
$ xe vm-param-get uuid=snip param-name=xenstore-data
vm-data/ddd.eee: fff; vm-data: ; vm-data/aaa-bbb: ccc; vm-data/foo: bar; vm-data/mmio-hole-size: 268435456



Boot VM

$ xe vm-param-get uuid=snip param-name=xenstore-data
vm-data: ; vm-data/mmio-hole-size: 268435456


# xenstore list vm-data


Wow! All entries I have added are gone.


I use CitrixHypervisor-8.2.0

$ xe host-param-list

software-version (MRO): product_version: 8.2.0;


Thanks in advance.


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No, a dot (period) is not an allowed character. See: https://xenbits.xen.org/docs/4.14-testing/misc/xenstore.txt



The permitted character for paths set is ASCII alphanumerics and plus the four punctuation characters -/_@ (hyphen slash underscore atsign). @ should be avoided except to specify special watches (see below). Doubled slashes and trailing slashes (except to specify the root) are forbidden. The empty path is also forbidden. Paths longer than 3072 bytes are forbidden; clients specifying relative paths should keep them to within 2048 bytes. (See XENSTORE_*_PATH_MAX in xs_wire.h.)



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