Le 28/02/2020 à 06:53, Pingfan Liu a écrit :
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.

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'.

Signed-off-by: Pingfan Liu <kernelf...@gmail.com>
To: linuxppc-...@lists.ozlabs.org
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Hari Bathini <hbath...@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
Cc: Oliver O'Halloran <ooh...@gmail.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: kexec@lists.infradead.org
---
note: I can not find such a pseries machine, and not finish it yet.
---
  arch/powerpc/platforms/pseries/papr_scm.c | 32 +++++++++++++++++++++----------
  1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c 
b/arch/powerpc/platforms/pseries/papr_scm.c
index c2ef320..555e746 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -382,7 +382,7 @@ static int papr_scm_probe(struct platform_device *pdev)
  {
        struct device_node *dn = pdev->dev.of_node;
        u32 drc_index, metadata_size;
-       u64 blocks, block_size;
+       u64 blocks, block_size, bound_addr = 0;
        struct papr_scm_priv *p;
        const char *uuid_str;
        u64 uuid[2];
@@ -439,17 +439,29 @@ static int papr_scm_probe(struct platform_device *pdev)
        p->metadata_size = metadata_size;
        p->pdev = pdev;
- /* request the hypervisor to bind this region to somewhere in memory */
-       rc = drc_pmem_bind(p);
+       of_property_read_u64(dn, "bound-addr", &bound_addr);
+       if (bound_addr)
+               p->bound_addr = bound_addr;
+       else {

All legs of an if/else must have { } when one leg need them, see codying style.

+               struct property *property;
+               u64 big;
- /* If phyp says drc memory still bound then force unbound and retry */
-       if (rc == H_OVERLAP)
-               rc = drc_pmem_query_n_bind(p);
+               /* request the hypervisor to bind this region to somewhere in 
memory */
+               rc = drc_pmem_bind(p);
- if (rc != H_SUCCESS) {
-               dev_err(&p->pdev->dev, "bind err: %d\n", rc);
-               rc = -ENXIO;
-               goto err;
+               /* If phyp says drc memory still bound then force unbound and 
retry */
+               if (rc == H_OVERLAP)
+                       rc = drc_pmem_query_n_bind(p);
+
+               if (rc != H_SUCCESS) {
+                       dev_err(&p->pdev->dev, "bind err: %d\n", rc);
+                       rc = -ENXIO;
+                       goto err;
+               }
+               big = cpu_to_be64(p->bound_addr);
+               property = new_property("bound-addr", sizeof(u64), &big,
+                       NULL);

Why plitting this line in two parts ? You have lines far longer above.
In powerpc we allow lines 90 chars long.

+               of_add_property(dn, property);
        }
/* setup the resource for the newly bound range */


Christophe

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