Re: [PATCH 02/21] ND NFIT-Defined/NVIDIMM Subsystem

From: Ingo Molnar
Date: Mon Apr 20 2015 - 03:06:36 EST



* Dan Williams <dan.j.williams@xxxxxxxxx> wrote:

> Maintainer information and documenation for drivers/block/nd/
>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Neil Brown <neilb@xxxxxxx>
> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> Documentation/blockdev/nd.txt | 867 +++++++++++++++++++++++++++++++++++++++++
> MAINTAINERS | 34 +-
> 2 files changed, 895 insertions(+), 6 deletions(-)
> create mode 100644 Documentation/blockdev/nd.txt
>
> diff --git a/Documentation/blockdev/nd.txt b/Documentation/blockdev/nd.txt
> new file mode 100644
> index 000000000000..bcfdf21063ab
> --- /dev/null
> +++ b/Documentation/blockdev/nd.txt
> @@ -0,0 +1,867 @@
> + The NFIT-Defined/NVDIMM Sub-system (ND)
> +
> + nd - kernel abi / device-model & ndctl - userspace helper library
> + linux-nvdimm@xxxxxxxxxxxx
> + v9: April 17th, 2015
> +
> +
> + Glossary
> +
> + Overview
> + Supporting Documents
> + Git Trees
> +
> + NFIT Terminology and NVDIMM Types
>
> [...]
>
> +The âNVDIMM Firmware Interface Tableâ (NFIT) [...]

Ok, I'll bite.

So why on earth is this whole concept and the naming itself
('drivers/block/nd/' stands for 'NFIT Defined', apparently) revolving
around a specific 'firmware' mindset and revolving around specific,
weirdly named, overly complicated looking firmware interfaces that
come with their own new weird glossary??

Firmware might be a discovery method - or not. A non-volatile device
might be e820 enumerated, or PCI discovered - potentially with all
discovery handled by the driver.

Why do you restrict this driver to a naming and design that is so
firmware centric?

Discovery matters, but what matters _most_ to devices is actually its
runtime properties and runtime implementation - and I sure hope
firmware has no active role in that!

I really think this is backwards from the get go, it gives me a
feeling of someone having spent way too much time in committee and too
little time spent thinking about simple, proper kernel design and
reusing existing terminology ...

Also:

+ nd - kernel abi / device-model & ndctl - userspace helper library

WTF is a 'kernel ABI'??

Thanks,

Ingo
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