On 3/4/20 2:17 PM, Pingfan Liu wrote:
At present, plpar_hcall(H_SCM_BIND_MEM, ...) takes a very long time, so if dumping to fsdax, it will take a very long time.
that should be fixed by faa6d21153fd11e139dd880044521389b34a24f2 Author: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> AuthorDate: Tue Sep 3 18:04:52 2019 +0530 Commit: Michael Ellerman <m...@ellerman.id.au> CommitDate: Wed Sep 25 08:32:59 2019 +1000 powerpc/nvdimm: use H_SCM_QUERY hcall on H_OVERLAP error Right now we force an unbind of SCM memory at drcindex on H_OVERLAP error. This really slows down operations like kexec where we get the H_OVERLAP error because we don't go through a full hypervisor re init. H_OVERLAP error for a H_SCM_BIND_MEM hcall indicates that SCM memory at drc index is already bound. Since we don't specify a logical memory address for bind hcall, we can use the H_SCM_QUERY hcall to query the already bound logical address.
Take a closer look, during the papr_scm initialization, the only configuration is through drc_pmem_bind()-> plpar_hcall(H_SCM_BIND_MEM, ...), which helps to set up the bound address. On pseries, for kexec -l/-p kernel, there is no reset of hardware, and this step can be stepped around to save times. So the pmem bound address can be passed to the 2nd kernel through a dynamic added property "bound-addr" in dt node 'ibm,pmemory'.
-aneesh
