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: <20190119132650.9978-1-anup.patel@wdc.com> <20190119132650.9978-7-anup.patel@wdc.com>
 <20190212070807.GD26747@infradead.org>
In-Reply-To: <20190212070807.GD26747@infradead.org>
From:   Anup Patel <anup@brainfault.org>
Date:   Tue, 12 Feb 2019 15:53:21 +0530
Message-ID: <CAAhSdy1NED22YyYrAJDqPkDqT1c2ms2QC9OjHP0qLwHT+o2zvg@mail.gmail.com>
Subject: Re: [PATCH v2 6/6] RISC-V: Implement keepinitrd kernel parameter
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Anup Patel <Anup.Patel@wdc.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Atish Patra <Atish.Patra@wdc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Feb 12, 2019 at 12:38 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Sat, Jan 19, 2019 at 01:28:59PM +0000, Anup Patel wrote:
> > This patch implements keepinitrd kernel parameter. By default,
> > keepinitrd=1 but users can pass "keepinitrd=0" to free-up
> > initrd memory at boot-time in free_initrd_mem() function.
> >
> > The keepinitrd kernel parameter is already implemented by
> > unicore32, arm, and arm64 architectures and it is documented
> > at: Documentation/admin-guide/kernel-parameters.txt
>
> But why do we need it?  Is there any good reason every not to free
> the initrd / initramfs memory when it is not used?

If it is initramfs (i.e. CPIO image) then contents of CPIO archive
are extracted to create a ramfs instance.

If it is initrd (i.e. some filesystem image) then RAM block device
is created in-place at initrd location. (Please correct me if I am
wrong about initrd here).

So in case of initrd we might not want to free-up the RAM but
we can certainly free-up in case of initramfs.

Regards,
Anup