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

- From: Stephan Müller \<hidden\>
- Date: 2014-09-14 18:22:36 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2014/09/4333351
- Thread: https://ratatoskr.run/linux-api/2014/09/4333338/t.md

```text
Am 14.09.2014 19:46, schrieb Greg KH:
> 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

I kind of expected this. The #ifndef __KERNEL__ was suspicious..

 thanks
```