commit c221c0b0308f ("device-dax: "Hotplug" persistent memory for use
like normal RAM") helps to add persistent memory as normal RAM blocks.
But this driver doesn't work if CONFIG_DEV_DAX_PMEM_COMPAT is enabled.
Here is the debugging call trace when CONFIG_DEV_DAX_PMEM_COMPAT is
enabled.
[ 4.443730] devm_memremap_pages+0x4b9/0x540
[ 4.443733] dev_dax_probe+0x112/0x220 [device_dax]
[ 4.443735] dax_pmem_compat_probe+0x58/0x92 [dax_pmem_compat]
[ 4.443737] nvdimm_bus_probe+0x6b/0x150
[ 4.443739] really_probe+0xf5/0x3d0
[ 4.443740] driver_probe_device+0x11b/0x130
[ 4.443741] device_driver_attach+0x58/0x60
[ 4.443742] __driver_attach+0xa3/0x140
Then the dax0.0 device will be registered as "nd" bus instead of
"dax" bus. This causes the error as follows:
root@ubuntu:~# echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
-bash: echo: write error: No such device
This gives a warning to notify the user.
Signed-off-by: Jia He <justin...@arm.com>
---
drivers/dax/kmem.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index ad62d551d94e..b77f0e880598 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -93,6 +93,11 @@ static struct dax_device_driver device_dax_kmem_driver = {
static int __init dax_kmem_init(void)
{
+ if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
+ pr_warn("CONFIG_DEV_DAX_PMEM_COMPAT is not compatible\n");
+ pr_warn("kmem dax driver might not be workable\n");
+ }
+
return dax_driver_register(&device_dax_kmem_driver);
}
--
2.17.1
