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Message-ID: <1524753932.3226.5.camel@HansenPartnership.com>
Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc
 fallback options
From:   James Bottomley <James.Bottomley@HansenPartnership.com>
To:     Mikulas Patocka <mpatocka@redhat.com>,
        Michal Hocko <mhocko@kernel.org>
Cc:     David Rientjes <rientjes@google.com>, dm-devel@redhat.com,
        eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org,
        jasowang@redhat.com, Randy Dunlap <rdunlap@infradead.org>,
        linux-kernel@vger.kernel.org, Matthew Wilcox <willy@infradead.org>,
        linux-mm@kvack.org, edumazet@google.com,
        Andrew Morton <akpm@linux-foundation.org>,
        virtualization@lists.linux-foundation.org,
        David Miller <davem@davemloft.net>,
        Vlastimil Babka <vbabka@suse.cz>
Date:   Thu, 26 Apr 2018 07:45:32 -0700
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On Thu, 2018-04-26 at 10:28 -0400, Mikulas Patocka wrote:
> 
> On Thu, 26 Apr 2018, Michal Hocko wrote:
> 
> > On Wed 25-04-18 18:42:57, Mikulas Patocka wrote:
> > > 
> > > 
> > > On Wed, 25 Apr 2018, James Bottomley wrote:
> > [...]
> > > > Kconfig proliferation, conversely, is a bit of a nightmare from
> both
> > > > the user and the tester's point of view, so we're trying to
> avoid it
> > > > unless absolutely necessary.
> > > > 
> > > > James
> > > 
> > > I already offered that we don't need to introduce a new kernel
> option and 
> > > we can bind this feature to any other kernel option, that is
> enabled in 
> > > the debug kernel, for example CONFIG_DEBUG_SG. Michal said no and
> he said 
> > > that he wants a new kernel option instead.
> > 
> > Just for the record. I didn't say I _want_ a config option. Do not
> > misinterpret my words. I've said that a config option would be
> > acceptable if there is no way to deliver the functionality via
> kernel
> > package automatically. You haven't provided any argument that would
> > explain why the kernel package cannot add a boot option. Maybe
> there are
> > some but I do not see them right now.
> 
> AFAIK Grub doesn't load per-kernel options from a per-kernel file.
> Even if we hacked grub scripts to add this option, other
> distributions won't.

Perhaps find out beforehand instead of insisting on an approach without
knowing.  On openSUSE the grub config is built from the files in
/etc/grub.d/ so any package can add a kernel option (and various
conditions around activating it) simply by adding a new file.  The
config files are quite sophisticated, so you can add what looks to be a
new kernel, but is really an existing kernel with different options
this way.

James