<div dir="ltr">I think something that anyone who isn&#39;t validating should be aware of is that cgminer(which powers the vast majority of the current mining network) doesn&#39;t allow for a pool to revert to mining on the previous block due to the way chain tracking is implemented.<br><br><a href="https://github.com/ckolivas/cgminer/blob/master/cgminer.c#L4727">https://github.com/ckolivas/cgminer/blob/master/cgminer.c#L4727</a><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 4, 2015 at 4:43 PM, Rusty Russell via bitcoin-dev <span dir="ltr">&lt;<a href="mailto:bitcoin-dev@lists.linuxfoundation.org" target="_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Gavin Andresen via bitcoin-dev &lt;<a href="mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfoundation.org</a>&gt;<br>
writes:<br>
<span class="">&gt; Overall, good idea.<br>
&gt;<br>
&gt; Is there a write-up somewhere describing in detail the &#39;accidental selfish<br>
&gt; mining&#39; problem that this mitigates? I think a link in the BIP to a fuller<br>
&gt; description of the problem and how validation-skipping makes it go away<br>
&gt; would be helpful.<br>
&gt;<br>
&gt; RE: which bit to use:  the draft versionbits BIP and BIP101 use bit 30; to<br>
&gt; avoid confusion, I think it would be better to use bit 0.<br>
<br>
</span>Yes, BIP9 need to be adjusted (setting bit 30 means BIP9 counts it as a<br>
vote against all softforks).  BIP101 uses bits 0,1,2 AFAICT, so perhaps<br>
start from the other end and use bit 29?  We can bikeshed that later<br>
though...<br>
<span class=""><br>
&gt; I agree with Jannes Faber, behavior with respect to SPV clients should be<br>
&gt; to only tell them about fully validated headers.<br>
<br>
</span>A delicate balance.  If we penalize these blocks too much, it&#39;s<br>
disincentive to set the bit.  Fortunately it&#39;s easy for SPV clients to<br>
decide for themselves, I think?<br>
<br>
Cheers,<br>
Rusty.<br>
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