On Fri, Jul 20, 2007 at 04:58:29PM -0700, Pete Zaitcev wrote:
> On Sat, 21 Jul 2007 02:04:34 +0300, Samuel Ortiz <[EMAIL PROTECTED]> wrote:
> > On Sat, Jul 21, 2007 at 12:04:27AM +0200, Oliver Neukum wrote:
>
> > > > +struct ks959_speedparams {
> > > > + __le32 baudrate; /* baud rate, little endian */
> > > > + unsigned int data_bits : 2; /* data bits - 5 (5..8) */
> > > > + unsigned int : 1;
> > > > + unsigned int stop_bits : 1;
> > > > + unsigned int parity_enable : 1;
> > > > + unsigned int parity_type : 1;
> > > > + unsigned int : 1;
> > > > + unsigned int reset : 1;
> > > > + __u8 reserved[3];
> > > > +} __attribute__ ((packed));
> > >
> > > The attribute is not needed.
>
> > The driver uses sizeof(struct ks959_speedparams) in a couple places in
> > the code. If you don't pack it, the size will vary with different
> > architectures since it's not 32 bits aligned, so I think this attribute
> > is correct.
>
> Oliver is correct, everything is perfectly aligned and the attribute
> is unnecessary.
Argghh, stupid me, should learn counting or something...the bit fields
take 1 byte, so the structure is indeed aligned.
So, yes, the packed attribute is not needed regardless of the compiler
reordering the bit fields or not.
> However the question is moot, since the bit fields vary in order.
> Bit fields must not be used, and shifts and masks must be used instead.
I didn't know about the bit field reordering, but it seems we should use
an __u8 and shift bits on it, yes.
Cheers,
Samuel.
> -- Pete
>
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