On 11.03.25 10:21, Julien Grall wrote:
Hi Juergen,On 11/03/2025 07:31, Juergen Gross wrote:In docs/misc/xenstore.txt all Xenstore commands are specified, but the specifications lack the numerical values of the commands. Add a table with all commands, their values, and a potential remark (e.g. whether the command is optional). Reported-by: Jan Beulich <jbeul...@suse.com> Signed-off-by: Juergen Gross <jgr...@suse.com> --- V2: - replace "ŕ" with plain "r" (Jan Beulich) - replace hard tabs with blanks (Jan Beulich) - allow GET_FEATURES and GET_QUOTA support without SET_* (Jan Beulich) --- docs/misc/xenstore.txt | 57 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/docs/misc/xenstore.txt b/docs/misc/xenstore.txt index 7e1f031520..8b4b790e11 100644 --- a/docs/misc/xenstore.txt +++ b/docs/misc/xenstore.txt@@ -86,6 +86,63 @@ parts of xenstore inaccessible to some clients. In any case passingbulk data through xenstore is not recommended as the performance properties are poor. +---------- Defined Xenstore message types ---------- + +Below is a table with all defined Xenstore message types (type name +and its associated numerical value). + +Some types are optional to be supported by a specific Xenstore +implementation. If an optional type is not supported by a Xenstore +implementation, Xen tools will continue to work, maybe with slightly +reduced functionality. A mandatory type not being supported will +result in severely reduced functionality, like inability to create +domains. In case a type is optional, this is stated in the table with +the lost functionality in case Xenstore doesn't support that type. + +XS_CONTROL 0 optional + If not supported, xenstore-control command will not work.Are we documenting anywhere how a user could figure out if the command is not supported? Is it a specific error code?
I can add that not supported commands will return "ENOSYS" as an error response.
+ XS_DEBUG is a deprecated alias of XS_CONTROL.> +XS_DIRECTORY 1> +XS_READ 2+XS_GET_PERMS 3 +XS_WATCH 4 +XS_UNWATCH 5 +XS_TRANSACTION_START 6 +XS_TRANSACTION_END 7 +XS_INTRODUCE 8 +XS_RELEASE 9 +XS_GET_DOMAIN_PATH 10 +XS_WRITE 11 +XS_MKDIR 12 +XS_RM 13 +XS_SET_PERMS 14 +XS_WATCH_EVENT 15 + Not valid in client sent messages. + Only valid in Xenstore replies. +XS_ERROR 16 + Not valid in client sent messages. + Only valid in Xenstore replies. +XS_IS_DOMAIN_INTRODUCED 17 +XS_RESUME 18 +XS_SET_TARGET 19 +XS_RESTRICT 20 no longer supported + XS_RESTRICT has been removed, the type value 20 is invalid. +XS_RESET_WATCHES 21 +XS_DIRECTORY_PART 22 optional + If not supported, the output of xenstore-ls might be incomplete + with more than ca. 1000 domains active.Why are we making this specific to number of domains? Wouldn't the problem be the same if you have 1000 node within a parent node?
Let me reiterate the answer I gave to Jan when he asked:
And elsewhere there can't be very many nodes resulting in a similar
situation?
Not without someone trying to force this by will (only possible by a
root user of dom0, e.g. via creating lots of nodes in the same directory
via "xenstore-write").
Having lots of domains is an "easy" way to create this scenario via
perfectly valid and sensible operations.
I can rephrase the remark like this:
If not supported, the output of xenstore-ls might be incomplete
with a node's sub-node list exceeding the maximum payload size
(e.g. the "/local/domain" node with more than ca. 1000 domains
active).
Juergen
OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key
OpenPGP_signature.asc
Description: OpenPGP digital signature
