From: "H. Peter Anvin" <hpa@zytor.com>
To: Tom Rini <trini@konsulko.com>, ron minnich <rminnich@gmail.com>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Borislav Petkov <bp@suse.de>,
Dominik Brodowski <linux@dominikbrodowski.net>
Subject: Re: [PATCH] initrd: Remove erroneous comment
Date: Mon, 22 Jun 2020 13:48:45 -0700 [thread overview]
Message-ID: <2455d1e8-d6b4-760b-9a4c-0071c5ae986d@zytor.com> (raw)
In-Reply-To: <20200622204034.GL27801@bill-the-cat>
On 2020-06-22 13:40, Tom Rini wrote:
> On Mon, Jun 22, 2020 at 01:02:16PM -0700, ron minnich wrote:
>
>> The other thing you ought to consider fixing:
>> initrd is documented as follows:
>>
>> initrd= [BOOT] Specify the location of the initial ramdisk
>>
>> for bootloaders only.
>>
>> UEFI consumes initrd from the command line as well. As ARM servers
>> increasingly use UEFI, there may be situations in which the initrd
>> option doesn't make its way to the kernel? I don't know, UEFI is such
>> a black box to me. But I've seen this "initrd consumption" happen.
>>
>> Based on docs, and the growing use of bootloaders that are happy to
>> consume initrd= and not pass it to the kernel, you might be better off
>> trying to move to the new command line option anyway.
>>
>> IOW, this comment may not be what people want to see, but ... it might
>> also be right. Or possibly changed to:
>>
>> /*
>> * The initrd keyword is in use today on ARM, PowerPC, and MIPS.
>> * It is also reserved for use by bootloaders such as UEFI and may
>> * be consumed by them and not passed on to the kernel.
>> * The documentation also shows it as reserved for bootloaders.
>> * It is advised to move to the initrdmem= option whereever possible.
>> */
>
> Fair warning, one of the other hats I wear is the chief custodian of the
> U-Boot project.
>
> Note that on most architectures in modern times the device tree is used
> to pass in initrd type information and "initrd=" on the command line is
> quite legacy.
>
> But what do you mean UEFI "consumes" initrd= ? It's quite expected that
> when you configure grub/syslinux/systemd-boot/whatever via extlinux.conf
> or similar with "initrd /some/file" something reasonable happens to
> read that in to memory and pass along the location to Linux (which can
> vary from arch to arch, when not using device tree). I guess looking at
> Documentation/x86/boot.rst is where treating initrd= as a file that
> should be handled and ramdisk_image / ramdisk_size set came from. I do
> wonder what happens in the case of ARM/ARM64 + UEFI without device tree.
>
UEFI plus the in-kernel UEFI stub is, in some ways, a "bootloader" in
the traditional sense. It is totally fair that we should update the
documentation with this as a different case, though, because it is part
of the kernel tree and so the kernel now has partial ownership of the
namespace.
I suggest "STUB" for "in-kernel firmware stub" for this purpose; no need
to restrict it to a specific firmware for the purpose of namespace
reservation.
-hpa
next prev parent reply other threads:[~2020-06-22 20:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 14:30 [PATCH] initrd: Remove erroneous comment Tom Rini
2020-06-19 17:49 ` [tip: x86/cleanups] " tip-bot2 for Tom Rini
2020-06-20 0:03 ` [PATCH] " ron minnich
2020-06-22 20:23 ` hpa
2020-06-22 20:02 ` ron minnich
2020-06-22 20:40 ` Tom Rini
2020-06-22 20:48 ` H. Peter Anvin [this message]
2020-06-22 21:06 ` Tom Rini
2020-06-22 20:56 ` ron minnich
2020-06-22 21:01 ` Tom Rini
2020-06-22 21:03 ` H. Peter Anvin
2020-06-22 21:07 ` Tom Rini
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