[U-Boot-Users] struct NS16550 {...} __attribute__ ((packed)) at ns16550.h

[Wolfgang Denk]

[Please do not send regular messages to the  u-boot-users-admin address!]

In message <OFC533536B.66CF098A-ONC1256FEE.002A2AD5-C1256FEE.002A9FFB at philips.com> you wrote:
> 
> Did you inspect the generated assembly statemens of __attribute__ 
> ((packed)) on the struct NS16650 when CFG_NS16550_REG_SIZE is 4? If you 

No, I did not.

> did then you would have noticed gcc (atleast 3.4.3 and 3.4.0) generates 
> byte access code for it. As I mailed to this mailinglist at the first of 

If this is really true, then there is either bug in GCC or in the code.
If I code a 32 bit access the compiler must not use any other accesses.

If CFG_NS16550_REG_SIZE is 4, then all entries  in  "struct  NS16550"
are  of  type  "unsigned long". All of the compilers I'm working with
generate exactly the same code whether "__attribute__ ((packed))"  is
used or not.

[BTW: at the moment only the U824 board uses  CFG_NS16550_REG_SIZE=4,
and this is a PowerPC board.]

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
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