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

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Message-Id: <20200716073843.e7b1921aae962da9e5714fe0@kernel.org>
Date:   Thu, 16 Jul 2020 07:38:43 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.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 Wed, 15 Jul 2020 16:45:04 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Thu, 16 Jul 2020 01:00:21 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > With this change, if the bootloader wants to change some value
> > in the default bootconfig, it doesn't need to parse the existing
> > bootconfig, but it can just append the new configs at the tail
> > of the bootconfig and update the footer (size, checksum and magic
> > word).
> 
> I wonder if we should support multiple bootconfigs instead of updating
> the size/checksum/magic?
> 
> 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.

Thank you,

-- 
Masami Hiramatsu <mhiramat@...nel.org>