linux-kernel - Re: [RFC PATCH 1/3] efi-rtc: Remove wakeup functionality

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f538a1b9-6a7c-474f-af2a-d87c35b82fc5@gmail.com>
Date: Mon, 14 Jul 2025 02:22:43 -0400
From: Demi Marie Obenour <demiobenour@...il.com>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org,
 Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
 Feng Tang <feng.tang@...ux.alibaba.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Juergen Gross <jgross@...e.com>, Stefano Stabellini
 <sstabellini@...nel.org>,
 Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
 Sunil V L <sunilvl@...tanamicro.com>, Bibo Mao <maobibo@...ngson.cn>,
 linux-rtc@...r.kernel.org, linux-efi@...r.kernel.org,
 xen-devel@...ts.xenproject.org, x86@...nel.org,
 linux-riscv@...ts.infradead.org, loongarch@...ts.linux.dev
Subject: Re: [RFC PATCH 1/3] efi-rtc: Remove wakeup functionality

On 7/14/25 02:19, Ard Biesheuvel wrote:
> On Mon, 14 Jul 2025 at 16:13, Demi Marie Obenour <demiobenour@...il.com> wrote:
>>
>> On 7/14/25 02:08, Ard Biesheuvel wrote:
>>> From: Ard Biesheuvel <ardb@...nel.org>
>>>
>>> The EFI rtc driver is used by non-x86 architectures only, and exposes
>>> the get/set wakeup time functionality provided by the underlying
>>> platform. This is usually broken on most platforms, and not widely used
>>> to begin with [if at all], so let's just remove it.
>> systemd uses the underlying functionality: a timer can wake the system up.
>> I have no idea if that is implemented in terms of this function, though.
> 
> To be clear, you are referring to wake from poweroff at some date/time
> in the future, right?

Yes.

> This change does not remove this functionality from the RTC subsystem,
> it just ceases to expose it on non-x86 EFI platforms that claim to
> support it.

Do these platforms generally expose the functionality in a different way?
If not, systemd should probably document that the functionality is
non-portable if it doesn't do that already.
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Download attachment "OpenPGP_0xB288B55FFF9C22C1.asc" of type "application/pgp-keys" (7141 bytes)

Download attachment "OpenPGP_signature.asc" of type "application/pgp-signature" (834 bytes)