Re: [PATCH RFC 0/7] block: Introduce CBD (CXL Block Device)

[Dan Williams]

Dongsheng Yang wrote:
> From: Dongsheng Yang <dongsheng.yang.linux@xxxxxxxxx>
> 
> Hi all,
> 	This patchset introduce cbd (CXL block device). It's based on linux 6.8, and available at:
> 	https://github.com/DataTravelGuide/linux
> 
[..]
> (4) dax is not supported yet:
> 	same with famfs, dax device is not supported here, because dax device does not support
> dev_dax_iomap so far. Once dev_dax_iomap is supported, CBD can easily support DAX mode.

I am glad that famfs is mentioned here, it demonstrates you know about
it. However, unfortunately this cover letter does not offer any analysis
of *why* the Linux project should consider this additional approach to
the inter-host shared-memory enabling problem.

To be clear I am neutral at best on some of the initiatives around CXL
memory sharing vs pooling, but famfs at least jettisons block-devices
and gets closer to a purpose-built memory semantic.

So my primary question is why would Linux need both famfs and cbd? I am
sure famfs would love feedback and help vs developing competing efforts.