‘packed’ attribute ignored for type ‘WORD *’...

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Pavel Skotak

• February 19, 2021 18:35

Hello friends,

i have working code for LPC1765 built with CrossStudio V2.1, where USB driver uses this construction:

*((__attribute__ ((packed)) WORD *)EP0Buf) = 0;

where EP0Buf is declared like:

BYTE EP0Buf[USB_MAX_PACKET0] __attribute__ ((aligned (4)));

(BYTE is unsigned char and WORD is unsigned short - USB driver is modified from NXP's example).

I moved to CrossStudio V4.8 recently and this code is not working anymore.

After compilation, there is warning:

‘packed’ attribute ignored for type ‘WORD *’ {aka ‘short unsigned int *’} [-Werror=attributes]

and if I set compiler to ignore warnigs or remove this attribute, USB device is not enumerated.

This behavior surprised me and I'm running out of time.

Can you help me?

Thanks in advance.

Pavel

 

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  Jon Elliott

  • February 22, 2021 12:16

  The packed attribute applies only to structs, unions or enums. The compiler is therefore correct in warning you that the packed attribute has been ignored in this case.

  This is a new warning in recent versions of gcc rather than a change in behaviour.

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  Pavel Skotak

  • February 22, 2021 17:20

  Hello Jon,

  thank you for reply. You are right. In the meantime, I found out that this is not the cause of the error. So something else has changed. I continue my search.

  Pavel.

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  Pavel Skotak

  • February 26, 2021 18:25

  Just for information - problem solved.

  I overlooked changes in default flash_placement.xml file in the V4.8.

  Recompilation with old flash placement file solved the problem.

  Happy coding.

  Pavel.

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