Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20191205005601.1559-1-anup.patel@wdc.com> <alpine.DEB.2.21.9999.1912041859070.215427@viisi.sifive.com>
 <CAAhSdy1RQw3MVcVT5y1EHr72LDNADKRL5nO2E8OrzBi+tpuvtA@mail.gmail.com> <20191205164706.svarpjp2kdokl2pg@holly.lan>
In-Reply-To: <20191205164706.svarpjp2kdokl2pg@holly.lan>
From:   Anup Patel <anup@brainfault.org>
Date:   Thu, 5 Dec 2019 22:39:59 +0530
Message-ID: <CAAhSdy3cMp8241Mcwb7tQCRd1LEzv9gKO2wyq8bctW86c0BVRg@mail.gmail.com>
Subject: Re: [PATCH] RISC-V: Add debug defconfigs
To:     Daniel Thompson <daniel.thompson@linaro.org>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <Anup.Patel@wdc.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Atish Patra <Atish.Patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Christoph Hellwig <hch@lst.de>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Dec 5, 2019 at 10:17 PM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Thu, Dec 05, 2019 at 10:03:34PM +0530, Anup Patel wrote:
> > On Thu, Dec 5, 2019 at 8:33 AM Paul Walmsley <paul.walmsley@sifive.com> wrote:
> > >
> > > On Thu, 5 Dec 2019, Anup Patel wrote:
> > >
> > > > Various Linux kernel DEBUG options have big performance impact
> > > > so these should not be enabled in RISC-V normal defconfigs.
> > > >
> > > > Instead we should have separate RISC-V debug defconfigs having
> > > > these DEBUG options enabled. This way Linux RISC-V can build both
> > > > non-debug and debug kernels separately.
> > >
> > > I respect your point of view, but until the RISC-V kernel port is more
> > > mature, I personally am not planning to merge this patch, for reasons
> > > discussed in the defconfig patch descriptions and the subsequent pull
> > > request threads.
> > >
> > > I'm sure we'll revisit this in the future to realign with the defconfig
> > > debug settings for more mature architecture ports - but my guess is that
> > > we'll probably avoid creating debug_defconfigs, since only S390 does that.
> >
> > We have a lot of users (Yocto and Buildroot) dependent on the Linux
> > defconfig. I understand that you need DEBUG options for SiFive internal
> > use but this does not mean all users dependent on Linux defconfig
> > should be penalized in-terms of performance.
> >
> > This is the right time to introduce debug defconfigs so that you can
> > use it for your SiFive internal use and all users dependent on normal
> > defconfigs are not penalized in-terms of performance.
> >
> > If you still don't want debug defconfigs then I recommend reverting
> > your DEBUG options patch and you can find an alternative way to
> > enable DEBUG options for SiFive internal use.
>
> None of my business (except that I watch threads with debug in the
> subject line) but why propose putting debug options into any kind
> of defconfig. If you want standardized set debug options to chase
> problems why can't they into a .config file rather than a defconfig
> file.
>
> In use it will look like:
>   make defconfig extra_debug.config
>
> That way you don't have to maintain two almost identical files that will
> inevitably drift apart.

This is a good suggestion. I will certainly try it out at my end and send
a v2 with "extra_debug.config" file.

Thanks,
Anup