linux-kernel - Re: [PATCH v2] efi: Allow to enable EFI runtime services by default on RT

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Message-ID: <19fa075a-cc5a-4127-389a-bab7812d7af3@redhat.com>
Date:   Fri, 1 Apr 2022 10:38:42 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        Brian Masney <bmasney@...hat.com>, Al Stone <ahs3@...hat.com>,
        Peter Robinson <pbrobinson@...il.com>,
        Robbie Harwood <rharwood@...hat.com>,
        Peter Jones <pjones@...hat.com>,
        Alexander Larsson <alexl@...hat.com>,
        Andrew Halaney <ahalaney@...hat.com>,
        linux-rt-users@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2] efi: Allow to enable EFI runtime services by default
 on RT

Hello Ard,

On 4/1/22 10:34, Ard Biesheuvel wrote:
> On Fri, 1 Apr 2022 at 10:33, Javier Martinez Canillas
> <javierm@...hat.com> wrote:

[snip]

>>
>>         if (!efi_enabled(EFI_RUNTIME_SERVICES))
>>                 efi.runtime_supported_mask = 0;
>> +       else if (IS_ENABLED(CONFIG_PREEMPT_RT))
>> +               pr_warn("EFI runtime services can lead to high latencies on Real-Time kernels\n");
>>
>>         if (!efi_enabled(EFI_BOOT))
>>                 return 0;
>>
> 
> 
> I don't think we need another warning.
> 
> The kernel log already tells you whether or not EFI runtime services
> are enabled.
> 

I'm fine with this too. As mentioned to Ahmed I was torn on this, since I
understand the ask for the warning but also don't want to pollute the log.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat