RE: [GIT preview] for-6.3/cxl-ram-region

[Dan Williams <dan.j.williams@intel.com>]

Dan Williams wrote:
> There are still some sharp edges on this patchset, like the missing
> device-dax hookup, but it is likely enough to show the direction and
> unblock other testing. Specifically I want to see how this fares with
> Greg's recent volatile region provisioning in QEMU.
> 
> I am hoping to have those last bits ironed out before the end of the
> week. Note that this topic branch will rebase so do not base any
> work beyond proof-of-concept on top of it.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git/log/?h=for-6.3/cxl-ram-region

I have updated this branch (14acf2db2613) with support for routing CXL
regions to System RAM. Will send the patches out once the build robot
finishes chewing on it.

With cxl_test and booting with "memhp_default_state=offline" (since
cxl_test is not real memory), it produces a device-dax instance that is
ready to be onlined via 'daxctl online-memory dax4.0':

# cxl list -RXu
{
  "region":"region4",
  "resource":"0xf010000000",
  "size":"512.00 MiB (536.87 MB)",
  "interleave_ways":2,
  "interleave_granularity":4096,
  "decode_state":"commit",
  "daxregion":{
    "id":4,
    "size":"512.00 MiB (536.87 MB)",
    "align":2097152,
    "devices":[
      {
        "chardev":"dax4.0",
        "size":"512.00 MiB (536.87 MB)",
        "target_node":0,
        "align":2097152,
        "mode":"system-ram",
        "online_memblocks":0,
        "total_memblocks":4
      }
    ]
  }
}