linux-kernel - Re: [PATCH 0/3] bootconfig: Add value override operator

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Message-ID: <20200715200212.0db61d5a@oasis.local.home>
Date:   Wed, 15 Jul 2020 20:02:12 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Alistair Delva <adelva@...gle.com>, linux-doc@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] bootconfig: Add value override operator

On Thu, 16 Jul 2020 07:38:43 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:


> > So the end of the initrd would have:
> > 
> >  [data][size/checksum/magic][more-data][size/checksum/magic]
> > 
> > 
> > And the kernel could do the following:
> > 
> >  1. read the end of the initrd for bootconfig
> >  2. If found parse the bootconfig data.
> >  3. look at the content before the bootconfig
> >  4. if another bootconfig exists, goto 2.
> >   
> 
> Yeah, that is possible. But since the total size of the bootconfig
> is limited to 32KB (this means data + 1st footer + more-data),
> I would like to give a chance of sanity check to the bootloader.


That's a limit of the size field, right?

The bootloader (and all tools including the kernel) could check for
multiple instances, and that would even increase the size of what can
be added. As each section would be 32KB max size, but there's no limit
to how many you have. All tools, bootconfig, the bootloader, and the
kernel can perform the checksum.

-- Steve