[RFC v1 0/9] kho: granular compatibility and header decoupling

[Pasha Tatashin]

On 06-08 21:11, Mike Rapoport wrote:
> On Mon, Jun 08, 2026 at 04:12:56PM +0000, Pasha Tatashin wrote:
> > On 06-08 13:26, Mike Rapoport wrote:
> > > On 2026-06-07 13:43:09+00:00, Pasha Tatashin wrote:
> >
> > Keeping all of that in a single KHO file is the wrong approach and goes 
> > against how other logically separated subsystems in Linux are organized 
> > (e.g., mm/vmap.c, mm/vmalloc.c, etc.). Yes, there are some messier 
> > places in the kernel as well, but keeping this in its own dedicated 
> > kho_vmalloc.c file makes complete sense to me.
> 
> Either I hallucinated or b4 ate a paragraph from my reply ;)
> 
> Regarding the code movement
> - splitting radix tree makes perfect sense to me, just the documentation
>   part needs more care than mechanical move

Agreed. I'll also pay closer attention to the documentation.

> - I'm fine with abi/vmalloc.h, presuming KHOSER_PTR() is not part of it

Yes, I will move KHOSER_PTR() to the shared compat.h in v2 so it's not 
tied to vmalloc.

> - I can live with kho_vmalloc.c although I still consider it unnecessary
>   churn

Appreciate it.

> - I'm against moving vmalloc APIs from kexec_handover.h because they are
>   very close in nature to folio and pages. I don't see core KHO as
>   responsible for preserving physically contiguous ranges but rather as
>   preserving allocations. Not sure we'll ever support kmalloc(), but still.

That is a very reasonable compromise. I am fine with keeping the 
consumer-facing function declarations in kexec_handover.h so they remain 
grouped  with folios and pages.

> > However, overall enforcing the use of KHOSER is unrelated to this work. 
> > I have my own thoughts on this, and perhaps with proper versioning, 
> > using KHOSER_PTR everywhere would be appropriate, but let's keep that as 
> > a separate work.
> 
> This is a separate work, indeed. But regardless of the versioning it's
> already better than plain u64 because it provides type safety.

Agreed.

Thanks!
Pasha