linux-kernel - Re: [PATCH] initramfs: Expose retained initrd as sysfs file

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Message-ID: <1ab3656e-bfed-441a-aa8c-c3bd816303e1@amazon.com>
Date:   Wed, 6 Dec 2023 22:29:30 +0100
From:   Alexander Graf <graf@...zon.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        "Jonathan Corbet" <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jan H.Schönherr <jschoenh@...zon.de>,
        James Gowans <jgowans@...zon.com>
Subject: Re: [PATCH] initramfs: Expose retained initrd as sysfs file


On 06.12.23 21:00, Andrew Morton wrote:
> On Wed, 6 Dec 2023 14:16:27 +0000 Alexander Graf <graf@...zon.com> wrote:
>
>> When the kernel command line option "retain_initrd" is set, we do not
>> free the initrd memory. However, we also don't expose it to anyone for
>> consumption. That leaves us in a weird situation where the only user of
>> this feature is ppc64 and arm64 specific kexec tooling.
>>
>> To make it more generally useful, this patch adds a kobject to the
>> firmware object that contains the initrd context when "retain_initrd"
>> is set. That way, we can access the initrd any time after boot from
>> user space and for example hand it into kexec as --initrd parameter
>> if we want to reboot the same initrd. Or inspect it directly locally.
> I think it would be helpful if the changelog were mention and describe
> the new /sys/firmware/initrd.  And I assume we should add a
> Documentation/ABI/testing/sysfs-firmware-initrd.


Thanks a bunch for the suggestions - let me send v2 with both addressed :)

Alex




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