RE: [PATCH 1/4] nvdimm: Add wrapper for IOCTL pass thru.

[Elliott, Robert (Persistent Memory)]

> -----Original Message-----
> From: Linux-nvdimm [mailto:linux-nvdimm-bounces@xxxxxxxxxxxx] On Behalf Of
> Hoemann, Jerry
> Sent: Friday, November 6, 2015 4:27 PM
> Subject: [PATCH 1/4] nvdimm: Add wrapper for IOCTL pass thru.
...
> diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h
...
> +struct ndn_pkg {
> +	struct {
> +		__u8	dsm_uuid[16];
> +		__u32	dsm_in;			/* size of _DSM input    */
> +		__u32	dsm_out;		/* size of user buffer   */
> +		__u32	dsm_rev;		/* revision of dsm call  */
> +		__u32	res[8];			/* reserved must be zero */
> +		__u32	dsm_size;		/* size _DSM would write */
> +	} h;
> +	unsigned char buf[];
> +} __packed;

Given that the _DSM arguments are defined as:
* Arg0 UUID: Buffer of 16 bytes
* Arg1 Revision ID: Integer (8 bytes)
* Arg2 Function Index: Integer (8 bytes)
* Arg3 Package: function-specific

1. The __u32 for dsm_rev is not big enough to express all
possible 8 byte Revision IDs.

2. The unsigned int cmd (carried outside this structure)
is not big enough on all platforms (e.g., 32-bit) to 
express all possible Function Indexes.

3. The Revision ID and Function Index values passed to 
the _DSM are defined as little-endian.  Are they
intended to use native endianness or be little-endian
in this structure?

---
Robert Elliott, HPE Persistent Memory



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