Re: [PATCH] Change userspace MKDEV, MAJOR, MINOR-macros from 8+8 bit, to 12+20 bit layout

From: Greg KH
Date: Sun Sep 14 2014 - 13:46:27 EST


On Sun, Sep 14, 2014 at 07:35:28PM +0200, Stephan Müller wrote:
> Delete old userspace-only versions (8+8 bit). Instead expose the kernel-space
> definitions (12+20 bit).
>
> Signed-off-by: Stephan Mueller <fruktopus@xxxxxxxxx>
> ---
>
> Browsing some code I found that user-space and kernel-space macros for (un-)packing major/minor device numbers differ. The user-space ones using still the old 16 bit scheme. There was no explaining comment around and most libraries have their own macros anyway so it should not be a problematic UAPI change. So IMHO we could win some coherence in abandon this discrepancy.
> Please correct me if I am wrong.

You are wrong, we can't change this api, things will break :(

sorry,

greg k-h
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