[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 25/28] libxl: emuids: Perhaps change dm xs control path
Ian Campbell writes ("Re: [PATCH 25/28] libxl: emuids: Perhaps change dm xs control path"): > So, do I understand correctly that the states (combinations of bits) are: No. > Describing SPLIT as an "ID" is a bit odd (it's a kind of meta thing) but I > suppose I can see why it is done this way. An alternative might be to have > a separate bit for the PV|DM case together, maybe you discarded that > possibility though? Perhaps things will be clearer with this comment, which I've just added to add in this patch: /* * This EMUID enum is used for several overlapping purposes. * * Each qemu process has an EMUID, which is either EMUID_PV or * EMUID_DM. * * Operations which talk to a qemu process need to know its emuid so * that they talk to the right one. (Specifically, so that they find * the right place in xenstore.) Likewise a qemu process needs to * be told its emuid for the same reason. * * However, qemut and older versions of qemuu do not support emuids. * In that case for an HVM domain, the same qemu process deals with * both roles. In this situation the xenstore paths for PV backend * control do not include the emuid, and therefore we can talk to the * single qemu `via' `both' emuids. * * In xenstore we record which qemus a domain has. This is necessary * for correct teardown. And, we also record whether the xenstore * paths are unified, as discussed above, so that subsequent libxl * operations can do the right thing. This is what the EMUID_SPLIT * flag is for. * * Overall, the following scenarios are possible: * * dm-emuidmap libxl__device_model_xs_path * can be passed control xs paths * which emuids? contain what * to distinguish * * 0 No QEMU processes PV - * PV PV domain PV - * PV HVM domain with stub dm PV; HVM stubdomid * DM HVM domain, 1 QEMU PV; HVM - * PV|DM|SPLIT HVM domain, 2 QEMUs privsep PV; HVM emuid * * The following scenarios would be handled correctly but are not set up * by current libxl code, and/or are implausible for other reasons: * * 0 Stub dm only HVM stubdomid * PV|SPLIT PV domain PV emuid */ Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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