[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAJMQK-iRKkOS9q-qGVj-3o6BVMeANrBoF_4MWQ1g-=4_6HRdbw@mail.gmail.com>
Date: Fri, 28 Jun 2019 19:47:20 +0800
From: Hsin-Yi Wang <hsinyi@...omium.org>
To: Mark Rutland <mark.rutland@....com>
Cc: "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@...ts.infradead.org>,
Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
lkml <linux-kernel@...r.kernel.org>,
Frank Rowand <frowand.list@...il.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Rapoport <rppt@...ux.ibm.com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Miles Chen <miles.chen@...iatek.com>,
James Morse <james.morse@....com>,
Andrew Murray <andrew.murray@....com>,
Jun Yao <yaojun8558363@...il.com>, Yu Zhao <yuzhao@...gle.com>,
Robin Murphy <robin.murphy@....com>,
Laura Abbott <labbott@...hat.com>,
Stephen Boyd <swboyd@...omium.org>,
Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v6 3/3] arm64: kexec_file: add rng-seed support
On Fri, Jun 28, 2019 at 5:42 PM Mark Rutland <mark.rutland@....com> wrote:
>
> On Wed, Jun 12, 2019 at 12:33:02PM +0800, Hsin-Yi Wang wrote:
> > Adding "rng-seed" to dtb. It's fine to add this property if original
> > fdt doesn't contain it. Since original seed will be wiped after
> > read, so use a default size 128 bytes here.
>
> Why is 128 bytes the default value?
More than 64 bytes should be enough.
>
> I didn't see an update to Documentation/devicetree/bindings/chosen.txt,
> so it's not clear to me precisely what we expect.
>
Rob suggested to update in a newer dt-schema documentation at
https://github.com/devicetree-org/dt-schema.
A pull request has been sent but perhaps it would continue if kernel
patches are accepted.
>
> For 128 bytes, it would be better to use a buffer on the stack. That
> avoids the possibility of the allocation failing.
>
Okay, I'll update this.
>
> If the RNG wasn't initialised, we'd carry on with a warning. Why do we
> follow a different policy here?
>
For failure case, I think kernel can still be boot since this is not a
very fatal case, just same as the seed wasn't provided by bootloader
at first boot. So I'll also let fdt_setprop() failed case carry on
with warning.
Thanks
Powered by blists - more mailing lists