From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH 04/37] atl1c: remove VPD register
Date: Sat, 14 Apr 2012 14:24:13 -0400 (EDT)
Message-ID: <20120414.142413.168675709062216981.davem@davemloft.net>
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Cc: xiong@qca.qualcomm.com, netdev@vger.kernel.org,
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From: Ben Hutchings <bhutchings@solarflare.com>
Date: Sat, 14 Apr 2012 15:22:49 +0100

> On Sat, 2012-04-14 at 09:12 +0000, Huang, Xiong wrote:
>> 
>> > -----Original Message-----
>> > From: David Miller [mailto:davem@davemloft.net]
>> > Sent: Saturday, April 14, 2012 8:46
>> > To: Huang, Xiong
>> > Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; qca-linux-team; nic-
>> > devel
>> > Subject: Re: [PATCH 04/37] atl1c: remove VPD register
>> > 
>> > From: xiong <xiong@qca.qualcomm.com>
>> > Date: Fri, 13 Apr 2012 08:14:29 +0800
>> > 
>> > > VPD register is only used for L1(devid=PCI_DEVICE_ID_ATTANSIC_L1) to
>> > > access external NV-memory.
>> > > l1c & later chip doesn't use it any more.
>> > >
>> > > Signed-off-by: xiong <xiong@qca.qualcomm.com>
>> > > Tested-by: Liu David <dwliu@qca.qualcomm.com>
>> > 
>> > You just broke ethtool register dumps with this change.
>> > 
>> > Now, all the initial registers are reported offset by one entry, yet the last two are
>> > still reported in their original spots.
>> > 
>> > This layout is exposed to userspace, and interpreted by tools, and you cannot
>> > change it.
>> > 
>> > If this register always reports some value, you should just keep it there in the
>> > dumps.
>> >
>> The VPD register doesn't report anything :(, just a dummy register now.
>> we don't have any special tools in userspace to explain the dumped registers.
>> Actually the purpose of dumping these registers via ethtool is just for debug.
> [...]
> 
> Of course, the whole purpose of the operation is for debugging.  But you
> should bump the dump version number (currently 0) every time you change
> the offsets of registers in the dump.

And also update the size, and not leave any holes between the actually
used register slots, etc.