Issue in netbsd_bootinfo.h

Issue in netbsd_bootinfo.h

[Seth Goldberg]

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?  Or did you mean to add "__attribute__((packed))" 
there?  The linker error is due to multiply-defined __packed symbols:

ld: fatal: symbol '__packed' is multiply-defined:
         (file loader/i386/bsd_module-bsd.o type=OBJT; file loader/i386/bsd_module-bsd32.o type=OBJT);
ld: fatal: symbol '__packed' is multiply-defined:
         (file loader/i386/bsd_module-bsd.o type=OBJT; file loader/i386/bsd_module-bsd64.o type=OBJT);
ld: fatal: file processing errors. No output written to bsd.module

  --S

Re: Issue in netbsd_bootinfo.h

[Grégoire Sutre]

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

Re: Issue in netbsd_bootinfo.h

[Seth Goldberg]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1465 bytes --]

Hi,

  Great.  My guess is: some linkers are more forgiving than others.  Can you 
get this fixed for non-Netbsd platforms where __packed is undefined, please?

  Thanks,
  --S

Quoting Grégoire Sutre, who wrote the following on Thu, 10 Nov 2011:

> 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
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>