[Barrelfish-users] Issue allocating RAM by user

[zhanqing Zhan(Qing)]

Dear All,
         I'm working to emulate a RAM allocator on barrelfish mem_serv.I used lib mm to initialize and allocate the RAM in mem_serv's way, but now I encountered a problem.
When I allocate a small RAM from a big block, we use slot_prealloc_refill function to refill a slab, then the refill func need to retype the node which is found in the mm_node tree. In this way, the node could not be retyped because it can't be looked up(Case 1: At first I used cnode_super to be the mem_cap which is not initialized in a user domain). Then I used the ACPI's way instead (I create a cnode and cnoderef to do cnode_super's job and also create the mem_cap from a RAM), when I use cap_copy to create a cap from RAM, it is INVALID to retype(case 2).


                                                                               Case1:
ERROR: failed to init slot allocator
Failure: (          libmm) Nested failure in slot allocator calling mm_alloc [MM_ERR_SLOT_MM_ALLOC]
Failure: (  libbarrelfish) Failure in cap_retype() [LIB_ERR_CAP_RETYPE]
Failure: (         kernel) Error looking up source capability [SYS_ERR_SOURCE_CAP_LOOKUP]
Failure: (         kernel) Capability not found (empty slot encountered) [SYS_ERR_CAP_NOT_FOUND]
Aborted


Case 2:
ERROR: failed to init slot allocator
Failure: (          libmm) Nested failure in slot allocator calling mm_alloc [MM_ERR_SLOT_MM_ALLOC]
Failure: (  libbarrelfish) Failure in cap_retype() [LIB_ERR_CAP_RETYPE]
Failure: (         kernel) Invalid source/destination type pair for retyping [SYS_ERR_INVALID_RETYPE]
Aborted


So, How mem_serv's mm_node struct define the cap?  (Is it the node's corresponding RAM which manages base & size or another thing?)
Which type the cap should be? Which type should I use? (CNode/RAM/Fram/...?)
How the cap's type transfer when I chunk a node?     (Because cap_retype defines the cap must be CNode type, and transfer to mm_ram's registed type. Should it transfer from CNODE to RAM?)

Best Regards
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