Re: [PATCH v2 8/8] block: Init for CBD(CXL Block Device) module

[Dongsheng Yang]

Hi Randy,

在 2024/9/25 星期三 上午 12:35, Randy Dunlap 写道:
> Hi.
>
> On 9/18/24 3:18 AM, Dongsheng Yang wrote:
> > diff --git a/drivers/block/cbd/Kconfig b/drivers/block/cbd/Kconfig
> > new file mode 100644
> > index 000000000000..16ffcca058c5
> > --- /dev/null
> > +++ b/drivers/block/cbd/Kconfig
> > @@ -0,0 +1,45 @@
> > +config BLK_DEV_CBD
> > +	tristate "CXL Block Device (Experimental)"
> > +	depends on DEV_DAX && FS_DAX
> > +	help
> > +	  CBD allows you to register a persistent memory device as a CBD transport.
> > +	  You can use this persistent memory as a data cache to improve your block
> > +	  device performance. Additionally, if you enable CBD_MULTIHOST, cbd allows
>
> s/cbd/CBD/ for consistency. Or does 'cbd' here explicitly refer to the loadable module
> name?

I will use uppercase "CBD" in the next version for consistency.
> > +	  you to access block devices on a remote host as if they were local disks.
> > +
> > +	  Select 'y' to build this module directly into the kernel.
> > +	  Select 'm' to build this module as a loadable kernel module.
>    +	  The module will be called cbd.
>
> > +
> > +	  If unsure say 'N'.
> > +
> > +config CBD_CRC
> > +	bool "Enable CBD checksum"
> > +	default N
>
> We usually omit 'default N' since that is the default default.

I explicitly added "default" here to make it clearer. In fact, I did a 
search:

find . -name 'Kconfig' -exec grep 'default n' {} + | wc -l

There are over 400+ of "default n" in the Kconfig files. （I will use 
'default n' in next version）
> > +	depends on BLK_DEV_CBD
> > +	help
> > +	  When CBD_CRC is enabled, all data sent by CBD will include
> > +	  a checksum. This includes a data checksum, a submit entry checksum,
> > +	  and a completion entry checksum. This ensures the integrity of the
> > +	  data transmitted through the CXL memory device.
> > +
> > +config CBD_DEBUG
> > +	bool "Enable CBD debug"
> > +	default N
>
> Ditto.
>
> > +	depends on BLK_DEV_CBD
> > +	help
> > +	  When CBD_DEBUG is enabled, cbd module will print more messages
> > +	  for debugging. But that will affact performance, so do not use it
>
> 	                               affect
>
> > +	  in production case.
> > +
> > +config CBD_MULTIHOST
> > +	bool "multi-hosts CXL Dlock Device"
>
> 	                      Block
>
> > +	default N
>
> drop default line.
>
> > +	depends on BLK_DEV_CBD
> > +	help
> > +	  When CBD_MULTIHOST is enabled, cbd allows the use of a shared memory device
>
> cbd or CBD?
>
> > +	  as a cbd transport. In this mode, the blkdev and backends on different
>
> ditto.
>
> > +	  hosts can be connected through the shared memory device, enabling cross-node
> > +	  disk access.
> > +
> > +	  IMPORTANT: This Require your shared memory device support Hardware-consistency
>
> 	                  requires                          supports
>
> > +	  as CXL 3.0 described.
>
> 	  as described in CXL 3.0.

agreed.

Thank you for your review.

Dongsheng
>