Hi,<div><br></div><div>I&#39;m a little bit confused by how Fiasco.OC sending capabilities through IPC. Particularly, it seems that one has to pack the capability in message register, rather than buffer register.</div><div>
<br></div><div>Here is a code sending some capability to the client, which works with Fiasco.OC:</div><div><br></div><div><div>l4_utcb_t * u = l4_utcb();</div><div>l4_utcb_mr_u(u)-&gt;mr[0] = ipc_id;</div><div>l4_utcb_mr_u(u)-&gt;mr[1] = L4_ITEM_MAP;</div>
<div>l4_utcb_mr_u(u)-&gt;mr[2] = l4_obj_fpage(cap, 0, L4_FPAGE_RWX).raw;</div><div>l4_utcb_br_u(u)-&gt;bdr = 0;</div></div><div>tag = l4_msgtag(label, 1, 1, 0);</div><div>ipc_call(...);</div><div><br></div><div>Notice that the capability is assigned into mr[1] and mr[2], but not br[1] and br[2].</div>
<div><br></div><div>It seems that this behavior is controlled by the constructor of L4_snd_item_iter, at kern/l4_buf_iter.cpp:52</div><div><br></div><div><div>  explicit L4_snd_item_iter(Utcb const *utcb, unsigned offset)</div>
<div>  : _buf(&amp;utcb-&gt;values[offset]),</div><div>    _max(&amp;utcb-&gt;values[Utcb::Max_words]) {}</div></div><div><br></div><div>My question is that whether this is the desired behavior? I didn&#39;t find any specification on this.</div>
<div><br></div><div>~Haohui</div>