Re: [RFC PATCH 07/20] famfs: Add include/linux/famfs_ioctl.h

[Randy Dunlap]

Hi John,

On 2/23/24 18:23, John Groves wrote:
>>> +
>>> +#define FAMFSIOC_MAGIC 'u'
>> This 'u' value should be documented in
>> Documentation/userspace-api/ioctl/ioctl-number.rst.
>>
>> and if possible, you might want to use values like 0x5x or 0x8x
>> that don't conflict with the ioctl numbers that are already used
>> in the 'u' space.
> Will do. I was trying to be too clever there, invoking "mu" for
> micron. 

I might have been unclear about this one.
It's OK to use 'u' but the values 1-4 below conflict in the 'u' space:

'u'   00-1F  linux/smb_fs.h                                          gone
'u'   20-3F  linux/uvcvideo.h                                        USB video class host driver
'u'   40-4f  linux/udmabuf.h

so if you could use
'u'   50-5f
or
'u'   80-8f

then those conflicts wouldn't be there.
HTH.

>>> +
>>> +/* famfs file ioctl opcodes */
>>> +#define FAMFSIOC_MAP_CREATE    _IOW(FAMFSIOC_MAGIC, 1, struct famfs_ioc_map)
>>> +#define FAMFSIOC_MAP_GET       _IOR(FAMFSIOC_MAGIC, 2, struct famfs_ioc_map)
>>> +#define FAMFSIOC_MAP_GETEXT    _IOR(FAMFSIOC_MAGIC, 3, struct famfs_extent)
>>> +#define FAMFSIOC_NOP           _IO(FAMFSIOC_MAGIC,  4)

-- 
#Randy