Re: [PATCH v6 01/12] iommu: Change type of pasid to u32

Fenghua Yu
2020-07-14T13:54:52Z

On Mon, Jul 13, 2020 at 07:45:49PM -0700, Liu, Yi L wrote:
> > From: Fenghua Yu <fenghua.yu@intel.com>
> > Sent: Tuesday, July 14, 2020 7:48 AM
> >
> > PASID is defined as a few different types in iommu including "int",
> > "u32", and "unsigned int". To be consistent and to match with uapi
> > definitions, define PASID and its variations (e.g. max PASID) as "u32".
> > "u32" is also shorter and a little more explicit than "unsigned int".
> >
> > No PASID type change in uapi although it defines PASID as __u64 in
> > some places.
>
> just out of curious, why not using ioasid_t? In Linux kernel, PASID is
> managed by ioasid.

ioasid_t is only used in limited underneath files (ioasid.c and ioasid.h).
Instead of changing hundreds of places to use ioasid_t, it's better to
keep ioasid_t only used in the files.

And it's explict and matches with uapi to define PASID as u32. Changing
to ioasid_t in so many files (amd, gpu, crypto, etc) may confuse upper
users on "why ioasid_t".

So we had better to explicitly define PASID as u32 and keep ioasid_t in
the limited underneath files.

Thanks.

-Fenghua