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SubjectRe: Getting past the 16-bit dev_t limitation.
Helge Hafting wrote:
> John Byrne wrote:
> > 1.) Can anyone tell me if there is a (Linus approved) solution in the
> > works for this for the 2.4.xx kernel series?
> > I am also curious whether there are plans to do away with the whole
> > concept of major/minor numbers;
> Consider reading up on devfs, which is now integrated into 2.4.
> Basically it is a (optional) special filesystem, where a driver register
> a
> name for each device it serves, possibly in a subdirectory.
> (I.e. all audio devices in /dev/sound/..., all scsi stuff under
> /dev/scsi/...)
> This device filesystem is mounted at /dev during boot, instead of having
> a
> /dev directory with special files.
> Helge Hafting

Both you and Martin told me to look as devfs. I had, but I looked again
to see what I had missed.

I had somehow missed that internally devfs allows majors and minors to
both be 16-bits. However, the interface to the kernel for this
information and thence to the user world is still looks to be the 16-bit
kdev_t; so exceeding 255 for your minor number would "bleed" onto your
major number and cause aliasing of devices in some cases. How bad the
effects would be, I don't know.


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