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

- From: Greg KH \<hidden\>
- Date: 2014-09-14 17:46:24 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2014/09/4333342
- Thread: https://ratatoskr.run/linux-api/2014/09/4333338/t.md

```text
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 <redacted>
> ---
> 
> 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
```