linux-kernel - Re: [PATCH 0/3] net: ethernet: atheros: atlx: Use PCI generic definitions instead of private duplicates

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Message-ID: <20190622085001.GA11032@arch>
Date:   Sat, 22 Jun 2019 14:20:01 +0530
From:   Puranjay Mohan <puranjay12@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Puranjay Mohan <puranjay12@...il.com>,
        Jay Cliburn <jcliburn@...il.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Bjorn Helgaas <bjorn@...gaas.com>,
        netdev <netdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Linux PCI <linux-pci@...r.kernel.org>,
        Chris Snook <chris.snook@...il.com>
Subject: Re: [PATCH 0/3] net: ethernet: atheros: atlx: Use PCI generic
 definitions instead of private duplicates

On Fri, Jun 21, 2019 at 11:33:27AM -0700, Joe Perches wrote:
> On Fri, 2019-06-21 at 13:12 -0500, Bjorn Helgaas wrote:
> > On Fri, Jun 21, 2019 at 12:27 PM Joe Perches <joe@...ches.com> wrote:
> []
> > > Subsystem specific local PCI #defines without generic
> > > naming is poor style and makes treewide grep and
> > > refactoring much more difficult.
> > 
> > Don't worry, we have the same objectives.  I totally agree that local
> > #defines are a bad thing, which is why I proposed this project in the
> > first place.
> 
> Hi again Bjorn.
> 
> I didn't know that was your idea.  Good idea.
> 
> > I'm just saying that this is a "first-patch" sort of learning project
> > and I think it'll avoid some list spamming and discouragement if we
> > can figure out the scope and shake out some of the teething problems
> > ahead of time.  I don't want to end up with multiple versions of
> > dozens of little 2-3 patch series posted every week or two.
> 
> Great, that's sensible.
> 
> > I'd rather be able to deal with a whole block of them at one time.
> 
> Also very sensible.
> 
> > > 2: Show that you compiled the object files and verified
> > >    where possible that there are no object file changes.
> > 
> > Do you have any pointers for the best way to do this?  Is it as simple
> > as comparing output of "objdump -d"?
> 
> Generically, yes.
> 
> I have a little script that does the equivalent of:
> 
> <git reset>
> make <foo.o>
> mv <foo.o> <foo.o>.old
> patch -P1 < <foo_patch>
> make <foo.o>
> mv <foo.o> <foo.o>.new
> diff -urN <(objdump -d <foo.o>.old) <(objdump -d <foo.o>.new)
> 
> But it's not foolproof as gcc does not guarantee
> compilation repeatability.
> 
> And some subsystems Makefiles do not allow per-file
> compilation.
>
Hi Joe,
I tried using your specified technique here are the steps I took and the
results I got.

I built the object file before the patch named it "atl2-old.o"
then I built it after the patch, named it "atl2-new.o"

then i ran these commands:-
$ objdump -d atl2-old.o > 1
$ objdump -d atl2-new.o > 2
$ diff -urN 1 2

--- 1	2019-06-22 13:56:17.881392372 +0530
+++ 2	2019-06-22 13:56:35.228018053 +0530
@@ -1,5 +1,5 @@

-atl2-old.o:     file format elf64-x86-64
+atl2-new.o:     file format elf64-x86-64


 Disassembly of section .text:

So both the object files are similar.

Thanks,
--Puranjay