[DRBD-user] DRBD - on ARM (armel)

Nick nickdrbd at alfiecam.co.uk
Thu Jun 11 12:02:41 CEST 2009

Please excuse my previous email with no details.... here is a patch that 
addresses the first issue I am seeing on the ARM platform.

This addresses the issue of the 'Unknown tag' error. As you suspected 
this is an alignment issue, if the data (in my case /dev/loop0 + NULL 
byte) has an odd size, the previous code failed to store the tag, for 
the subsequent parameter, due to the data pointer not falling on a word 
boundary. This fixes it for ARM, and it continues to work on i386, 
however I am not sure about other platforms, perhaps this would be an 
issue on big endian platforms, since the add_tag function takes the tag 
and size as an int, rather than a short.

Hopefully this will be the only issue I have!



-- drbdsetup.c.orig    2009-06-11 10:51:08.000000000 +0100
+++ drbdsetup.c    2009-06-11 10:53:43.000000000 +0100
@@ -549,8 +549,8 @@
        fprintf(stderr, "Tag list size exceeded!\n");
-    *tl->tag_list_cpos++ = tag;
-    *tl->tag_list_cpos++ = data_len;
+    memcpy(tl->tag_list_cpos++, (short*)&tag, sizeof(tl->tag_list_cpos));
+    memcpy(tl->tag_list_cpos++, (short*)&data_len, 
    tl->tag_list_cpos = (unsigned short*)((char*)tl->tag_list_cpos + 

Lars Ellenberg wrote:
> On Wed, Jun 10, 2009 at 02:04:06PM +0100, Nick Liebmann wrote:
>> Thanks for the speedy response Lars, I have patched my kernel module 
>> (its 8.3.1, so I just changed the kmalloc to a kzalloc...I hope that is 
>> OK), and now no longer suffer from the kernel Oops.. great, but 
>> unfortunately I am still getting the  REAL problem
>> kernel: drbd0: Unknown tag: 1071
>> nasty:~# drbdadm attach r0
>> 0: Failure: (126) UnknownMandatoryTag
>> Command 'drbdsetup 0 disk /dev/loop0 /dev/loop0 internal --set-defaults --create-device' terminated with exit code 10
>> I have found no reference to this on the mailing lists, any ideas what is going on here?
> nope.
> maybe alignment issues.
> maybe a build problem.
> you need to debug that.

More information about the drbd-user mailing list