Re: [RFC 06/13] rust: add bindings for memattrs

[Zhao Liu]

On Thu, Dec 05, 2024 at 05:51:42PM -0600, Richard Henderson wrote:
> Date: Thu, 5 Dec 2024 17:51:42 -0600
> From: Richard Henderson <richard.henderson@linaro.org>
> Subject: Re: [RFC 06/13] rust: add bindings for memattrs
> 
> On 12/5/24 12:30, Paolo Bonzini wrote:
> > On 12/5/24 19:15, Richard Henderson wrote:
> > > On 12/5/24 00:07, Zhao Liu wrote:
> > > > The MemTxAttrs structure is composed of bitfield members, and bindgen is
> > > > unable to generate an equivalent macro definition for
> > > > MEMTXATTRS_UNSPECIFIED.
> > > 
> > > I'm happy to move away from bit fields to uint32_t or suchlike to
> > > enable MEMTXATTRS_UNSPECIFIED be a compile-time constant.
> > 
> > Yeah, if we go from
> > 
> > typedef struct MemTxAttrs {
> >      unsigned int unspecified:1;
> >      unsigned int secure:1;
> >      unsigned int space:2;
> >      unsigned int user:1;
> >      unsigned int memory:1;
> >      unsigned int requester_id:16;
> >      unsigned int pid:8;
> > } MemTxAttrs;
> > 
> > to
> > 
> > typedef struct MemTxAttrs {
> >      uint8_t unspecified;
> >      uint8_t secure;
> >      uint8_t space;
> >      uint8_t user;
> >      uint8_t memory;
> >      uint8_t pid;
> >      uint16_t requester_id;
> > } MemTxAttrs;
> > 
> > is still decently packed and simplifies things a lot.  Zhao, can you
> > submit that as an independent patch?
> Hmm.  I'd been thinking of uint32_t and hw/registerfields.h, but I have not
> scoped the size of that conversion.
> 
> But short of that, please use 'bool' not 'uint8_t' for those single-bit flags.
> 

Sure! Thank u both!

BTW, may I ask why you favor bool over uint8_t, and is it because they
are indeed just 0/1 as well? :)

Thanks,
Zhao