linux-kernel - Re: [PATCH] PM / reboot: Use S5 for reboot

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: <f8e03d98-1732-81f8-9557-a5da8f962368@redhat.com>
Date:   Fri, 30 Oct 2020 11:01:39 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        linux-acpi@...r.kernel.org, Petr Mladek <pmladek@...e.com>,
        Mike Rapoport <rppt@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Kees Cook <keescook@...omium.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM / reboot: Use S5 for reboot

Hi,

On 10/30/20 8:09 AM, Kai-Heng Feng wrote:
> Hi Hans,
> 
>> On Oct 30, 2020, at 15:06, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
>>
>> After reboot, it's not possible to use hotkeys to enter BIOS setup and
>> boot menu on some HP laptops.
>>
>> BIOS folks identified the root cause is the missing _PTS call, and BIOS
>> is expecting _PTS to do proper reset.
>>
>> Using S5 for reboot is default behavior under Windows, "A full shutdown
>> (S5) occurs when a system restart is requested" [1], so let's do the
>> same here.
> 
> I wonder if this can also solve "HID: i2c-hid: Put ACPI enumerated devices in D3 on shutdown" fixed.

I just checked the _PTS of one of the devices with the SMO91D0 i2c-hid
sensor-hub and it does not appear to turn off the sensor-hub (or any
other devices for that matter). Specifically it does not touch the
GPIO used by the _PS0 / _PS3 methods of the SMO91D0.

Regards,

Hans




>> [1] https://docs.microsoft.com/en-us/windows/win32/power/system-power-states
>>
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> kernel/reboot.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/reboot.c b/kernel/reboot.c
>> index e7b78d5ae1ab..7e5aa1f78693 100644
>> --- a/kernel/reboot.c
>> +++ b/kernel/reboot.c
>> @@ -244,6 +244,8 @@ void migrate_to_reboot_cpu(void)
>> void kernel_restart(char *cmd)
>> {
>> 	kernel_restart_prepare(cmd);
>> +	if (pm_power_off_prepare)
>> +		pm_power_off_prepare();
>> 	migrate_to_reboot_cpu();
>> 	syscore_shutdown();
>> 	if (!cmd)
>> -- 
>> 2.17.1
>>
>