Re: Re: [PATCH v2 3/3] efi: Capsule update with user helper interface

From: Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
To: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Cc: Peter Jones <pjones-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"Kweh,
	Hock Leong"
	<hock.leong.kweh-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Sam Protsenko
	<semen.protsenko-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Ming Lei <ming.lei-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	"Ong,
	Boon Leong"
	<boon.leong.ong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: Re: [PATCH v2 3/3] efi: Capsule update with user helper interface
Date: Thu, 12 Mar 2015 22:47:54 +0000	[thread overview]
Message-ID: <20150312224754.GD24174@codeblueprint.co.uk> (raw)
In-Reply-To: <CALCETrUDuTt_BK1JSFU=_EEujpm1ekzmkte-c3vxuRW7hWPUPQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, 10 Mar, at 08:51:59AM, Andy Lutomirski wrote:
> 
> I'm not 100% happy with write(2) (which is all we have in sysfs) for
> two reasons:
> 
> 1. If we write a file name, eww.  That's more complicated, requires
> temporary files, has annoying mount namespace issues, etc.
> 
> 2. If we write the full contents, we need to do it in a single call to
> write.  That means that we can't use cat, which mostly defeats the
> purpose.  In fact, using cat could be actively harmful.

At this point I'd really like Greg to chime in.

In principal, I'm not stricly opposed to using a simple char device
provided that it's not essentially a copy and paste of code from
drivers/base/firmware_class.c.

Greg?

-- 
Matt Fleming, Intel Open Source Technology Center