Re: Issue in netbsd_bootinfo.h

["Grégoire Sutre" <gregoire.sutre@gmail.com>]

On 11/09/2011 01:14 AM, Seth Goldberg wrote:
> Hi,
>
> The following structure definition is causing linker failures (not with GNU
> ld) when building GRUB2:
>
> struct grub_netbsd_btinfo_bootwedge {
> grub_uint32_t biosdev;
> grub_disk_addr_t startblk;
> grub_uint64_t nblks;
> grub_disk_addr_t matchblk;
> grub_uint64_t matchnblks;
> grub_uint8_t matchhash[16]; /* MD5 hash */
> } __packed;
>
>
> The question is: Is this a valid way to declare a structure with a packed
> data structure on NetBSD?

Yes.  IIRC, this struct declaration was inspired from:

http://nxr.netbsd.org/xref/src/sys/arch/x86/include/bootinfo.h#70

 > Or did you mean to add "__attribute__((packed))"
> there?

Indeed, you're right.  NetBSD defines __packed depending on the
compiler:

http://nxr.netbsd.org/source/xref/src/sys/sys/cdefs.h#314

For GCC, it's "__attribute__((__packed__))" as you said.  Sorry
about that.  I wonder why it didn't cause problems until now, though.

Grégoire