Fan Ni wrote: > On Sun, Apr 13, 2025 at 05:52:08PM -0500, Ira Weiny wrote: > > A git tree of this series can be found here: > > > > https://github.com/weiny2/linux-kernel/tree/dcd-v6-2025-04-13 > > > > This is now based on 6.15-rc2. > > > > Due to the stagnation of solid requirements for users of DCD I do not > > plan to rev this work in Q2 of 2025 and possibly beyond. > > > > It is anticipated that this will support at least the initial > > implementation of DCD devices, if and when they appear in the ecosystem. > > The patch set should be reviewed with the limited set of functionality in > > mind. Additional functionality can be added as devices support them. > > > > It is strongly encouraged for individuals or companies wishing to bring > > DCD devices to market review this set with the customer use cases they > > have in mind. > > Hi Ira, > thanks for sending it out. > > I have not got a chance to check the code or test it extensively. > > I tried to test one specific case and hit issue. > > I tried to add some DC extents to the extent list on the device when the > VM is launched by hacking qemu like below, > > diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c > index 87fa308495..4049fc8dd9 100644 > --- a/hw/mem/cxl_type3.c > +++ b/hw/mem/cxl_type3.c > @@ -826,6 +826,11 @@ static bool cxl_create_dc_regions(CXLType3Dev *ct3d, > Error **errp) > QTAILQ_INIT(&ct3d->dc.extents); > QTAILQ_INIT(&ct3d->dc.extents_pending); > > + cxl_insert_extent_to_extent_list(&ct3d->dc.extents, 0, > + CXL_CAPACITY_MULTIPLIER, NULL, 0); > + ct3d->dc.total_extent_count = 1; > + ct3_set_region_block_backed(ct3d, 0, CXL_CAPACITY_MULTIPLIER); > + > return true; > } > > > Then after the VM is launched, I tried to create a DC region with > commmand: cxl create-region -m mem0 -d decoder0.0 -s 1G -t > dynamic_ram_a. > > It works fine. As you can see below, the region is created and the > extent is showing correctly. > > root@debian:~# cxl list -r region0 -N > [ > { > "region":"region0", > "resource":79725330432, > "size":1073741824, > "interleave_ways":1, > "interleave_granularity":256, > "decode_state":"commit", > "extents":[ > { > "offset":0, > "length":268435456, > "uuid":"00000000-0000-0000-0000-000000000000" > } > ] > } > ] > > > However, after that, I tried to create a dax device as below, it failed. > > root@debian:~# daxctl create-device -r region0 -v > libdaxctl: __dax_regions_init: no dax regions found via: /sys/class/dax > error creating devices: No such device or address > created 0 devices > root@debian:~# > > root@debian:~# ls /sys/class/dax > ls: cannot access '/sys/class/dax': No such file or directory
Have you update daxctl with cxl-cli? I was confused by this lack of /sys/class/dax and checked with Vishal. He says this is legacy. I have /sys/bus/dax and that works fine for me with the latest daxctl built from the ndctl code I sent out: https://github.com/weiny2/ndctl/tree/dcd-region3-2025-04-13 Could you build and use the executables from that version? Ira > > The dmesg shows the really_probe function returns early as resource > presents before probe as below, > > [ 1745.505068] cxl_core:devm_cxl_add_dax_region:3251: cxl_region region0: > region0: register dax_region0 > [ 1745.506063] cxl_pci:__cxl_pci_mbox_send_cmd:263: cxl_pci 0000:0d:00.0: > Sending command: 0x4801 > [ 1745.506953] cxl_pci:cxl_pci_mbox_wait_for_doorbell:74: cxl_pci > 0000:0d:00.0: Doorbell wait took 0ms > [ 1745.507911] cxl_core:__cxl_process_extent_list:1802: cxl_pci 0000:0d:00.0: > Got extent list 0-0 of 1 generation Num:0 > [ 1745.508958] cxl_core:__cxl_process_extent_list:1815: cxl_pci 0000:0d:00.0: > Processing extent 0/1 > [ 1745.509843] cxl_core:cxl_validate_extent:975: cxl_pci 0000:0d:00.0: DC > extent DPA [range 0x0000000000000000-0x000000000fffffff] (DCR:[range > 0x0000000000000000-0x000000007fffffff])(00000000-0000-0000-0000-000000000000) > [ 1745.511748] cxl_core:__cxl_dpa_to_region:2869: cxl decoder2.0: dpa:0x0 > mapped in region:region0 > [ 1745.512626] cxl_core:cxl_add_extent:460: cxl decoder2.0: Checking ED ([mem > 0x00000000-0x3fffffff flags 0x80000200]) for extent [range > 0x0000000000000000-0x000000000fffffff] > [ 1745.514143] cxl_core:cxl_add_extent:492: cxl decoder2.0: Add extent [range > 0x0000000000000000-0x000000000fffffff] (00000000-0000-0000-0000-000000000000) > [ 1745.515485] cxl_core:online_region_extent:176: extent0.0: region extent > HPA [range 0x0000000000000000-0x000000000fffffff] > [ 1745.516576] cxl_core:cxlr_notify_extent:285: cxl dax_region0: Trying > notify: type 0 HPA [range 0x0000000000000000-0x000000000fffffff] > [ 1745.517768] cxl_core:cxl_bus_probe:2087: cxl_region region0: probe: 0 > [ 1745.524984] cxl dax_region0: Resources present before probing > > > btw, I hit the same issue with the previous verson also. > > Fan [snip]
