linux-kernel - Re: [PATCH v2] initramfs: Expose retained initrd as sysfs file

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Message-ID: <ZXPiregue0FkxDEs@archie.me>
Date:   Sat, 9 Dec 2023 10:44:45 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Alexander Graf <graf@...zon.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:     Linux Documentation <linux-doc@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.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 v2] initramfs: Expose retained initrd as sysfs file

On Fri, Dec 08, 2023 at 12:54:18AM +0100, Alexander Graf wrote:
> Hi Bagas,
> 
> On 07.12.23 13:37, Bagas Sanjaya wrote:
> > On my Arch Linux system, /sys/firmware/initrd is not same as initramfs image
> > from /boot partition that is uncompressed. `ls -l` listing shows
> > (with /tmp/initramfs-boot is unzstd'ed initramfs of the same kernel booted):
> > 
> > ```
> > -r--r----- 1 root root 22967535 Dec  7 19:32 /sys/firmware/initrd
> > -rw------- 1 root root 40960000 Dec  7 19:26 /tmp/initramfs-boot
> > ```
> > 
> > And thus, `cpio -i -v` listing differs. While in uncompressed initramfs,
> > I got expected initramfs contents (early userpace for booting), doing the same
> > to /sys/firmware/initrd only shows Intel microcode.
> > 
> > Regardless, exposing initramfs as advertised in the patch description works for
> > me.
> 
> 
> Thanks a bunch for testing the patch!
> 
> The reason you're seeing microcode is that something in your boot chain
> (grub maybe? sd-boot?) sends multiple initrd blobs to Linux: One that
> contains microcode and another that contains the real initrd. Linux
> continues extracting past the first cpio archive.
> 

Yes, I use grub on my setup.

Ciao!

-- 
An old man doll... just what I always wanted! - Clara

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