<br><font size=2 face="sans-serif">Hi Roland,</font>
<br>
<br><font size=2 face="sans-serif">Could you tell me what's the difference
between "wmb()" and "mmiowb()". I notice that ofa-1.3
has added "mmiowb()" at the end of mthca_cmd_post, since "wmb()"
is already called at the end of cmd_post, is "mmiowb()" really
necessary?</font>
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<br><font size=2 face="sans-serif">Thanks!</font>
<br><font size=2 face="sans-serif">Yicheng</font>
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<td width=40%><font size=1 face="sans-serif"><b>Roland Dreier <rdreier@cisco.com></b>
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<p><font size=1 face="sans-serif">01/02/2008 12:13 PM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">Jack Morgenstein <jackm@dev.mellanox.co.il></font>
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<div align=right><font size=1 face="sans-serif">cc</font></div>
<td><font size=1 face="sans-serif">general@lists.openfabrics.org, Yicheng
Jia <YJia@tmriusa.com></font>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [ofa-general] synchronize commands
issued to MTHCA</font></table>
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<br><tt><font size=2> > Roland, do you think that the memcpy_toio()
call might mess things up?<br>
<br>
I wouldn't think so, although I don't have full details of how your<br>
hardware behaves to know for sure. I assume your PCI bus/memory<br>
controller is already smart enough to deal with HCR writes being<br>
interleaved with writes to a doorbell page from userspace, so it seems<br>
that writes to locally attached memory should be OK too, as long as<br>
the HCR writes are word-sized in the right order etc.<br>
<br>
> Maybe we need "wmb()" or "mmiowb()" here as well?<br>
<br>
I don't see any reason, although I often miss things. It seems that<br>
the only thing that cares about the writes of the address info being<br>
done would be posting a send WQE that uses it, and that should already<br>
have sufficient ordering. What would we be ordering things against?<br>
<br>
- R.<br>
<br>
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