From: Henry Wang Date: Fri, 24 May 2024 22:55:22 +0000 (-0700) Subject: docs/features/dom0less: Update the late XenStore init protocol X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=9cc1892bed7adb796b87f023e4bd99b9f0de1707;p=people%2Froyger%2Fxen.git docs/features/dom0less: Update the late XenStore init protocol With the new allocation strategy of Dom0less DomUs XenStore page, update the doc of the late XenStore init protocol accordingly. Signed-off-by: Henry Wang Signed-off-by: Stefano Stabellini Reviewed-by: Michal Orzel --- diff --git a/docs/features/dom0less.pandoc b/docs/features/dom0less.pandoc index 725afa0558..8b178edee0 100644 --- a/docs/features/dom0less.pandoc +++ b/docs/features/dom0less.pandoc @@ -110,9 +110,10 @@ hotplug PV drivers to dom0less guests. E.g. xl network-attach domU. The implementation works as follows: - Xen allocates the xenstore event channel for each dom0less domU that has the "xen,enhanced" property, and sets HVM_PARAM_STORE_EVTCHN -- Xen does *not* allocate the xenstore page and sets HVM_PARAM_STORE_PFN - to ~0ULL (invalid) -- Dom0less domU kernels check that HVM_PARAM_STORE_PFN is set to invalid +- Xen allocates the xenstore page and sets HVM_PARAM_STORE_PFN as well + as the connection status to XENSTORE_RECONNECT. +- Dom0less domU kernels check that HVM_PARAM_STORE_PFN is set to + ~0ULL (invalid) or the connection status is *not* XENSTORE_CONNECTED. - Old kernels will continue without xenstore support (Note: some old buggy kernels might crash because they don't check the validity of HVM_PARAM_STORE_PFN before using it! Disable "xen,enhanced" in @@ -121,13 +122,14 @@ The implementation works as follows: channel (HVM_PARAM_STORE_EVTCHN) before continuing with the initialization - Once dom0 is booted, init-dom0less is executed: - - it allocates the xenstore shared page and sets HVM_PARAM_STORE_PFN + - it gets the xenstore shared page from HVM_PARAM_STORE_PFN - it calls xs_introduce_domain - Xenstored notices the new domain, initializes interfaces as usual, and sends an event channel notification to the domain using the xenstore event channel (HVM_PARAM_STORE_EVTCHN) - The Linux domU kernel receives the event channel notification, checks - HVM_PARAM_STORE_PFN again and continue with the initialization + HVM_PARAM_STORE_PFN and the connection status again and continue with + the initialization Limitations