Re: [RFC 1/8] drivers: add generic remoteproc framework

[Russell King - ARM Linux]

On Mon, Jun 27, 2011 at 02:49:58PM -0600, Grant Likely wrote:
> > +struct {
> > +      char magic[4] = { 'R', 'P', 'R', 'C' };
> > +      u32 version;
> > +      u32 header_len;
> > +      char header[...] = { header_len bytes of unformatted, textual header };
> > +      struct section {
> > +          u32 type;
> > +          u64 da;
> > +          u32 len;
> > +          u8 content[...] = { len bytes of binary data };
> > +      } [ no limit on number of sections ];
> > +} __packed;
> 
> Other have commented on the image format, so I'll skip this bit other
> than saying that I agree it would be great to have a common format.

(Don't have the original message to reply to...)

Do we really want to end up with header being 5 bytes, header_len set
as 5, and having to load/store all this data using byte loads/stores ?

If we don't want that, then I suggest we get rid of the packed attribute,
and require stuff to be naturally aligned.

First issue is that struct section could be much better layed out:

struct section {
	u32 type;
	u32 len;
	u64 da;
	u8 content[];
};

and require sizeof(struct section) % sizeof(u64) == 0 - iow, to find
the next section, round len up to sizeof(u64).  Ditto for the header.
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