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Thu, 31 Mar 2022 07:25:43 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz+nCts91Ox2v33cXyUxStj+G8bKWgtO7ypFuFQU85nR93l+pGlLswqWvSuB4F5iAFTSK9ljg== X-Received: by 2002:a05:600c:4f10:b0:38c:ae36:d305 with SMTP id l16-20020a05600c4f1000b0038cae36d305mr5062017wmq.34.1648736743225; Thu, 31 Mar 2022 07:25:43 -0700 (PDT) Received: from [192.168.1.102] ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id j16-20020a05600c191000b0038ca3500494sm12809273wmq.27.2022.03.31.07.25.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 31 Mar 2022 07:25:41 -0700 (PDT) Message-ID: Date: Thu, 31 Mar 2022 16:25:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] efi: Allow to enable EFI runtime services with PREEMPT_RT Content-Language: en-US To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Peter Jones , Alexander Larsson , Al Stone , linux-efi@vger.kernel.org, Ard Biesheuvel , Andrew Halaney , linux-rt-users@vger.kernel.org, Brian Masney , Robbie Harwood , Thomas Gleixner References: <20220331141038.171204-1-javierm@redhat.com> From: Javier Martinez Canillas In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Sebastian, On 3/31/22 16:13, Sebastian Andrzej Siewior wrote: > On 2022-03-31 16:10:38 [+0200], Javier Martinez Canillas wrote: >> Commit d9f283ae71af ("efi: Disable runtime services on RT") disabled EFI >> runtime services when the CONFIG_PREEMPT_RT option is enabled. >> >> The rationale for the change is that some EFI calls could take too much >> time, leading to large latencies which are an issue for RT kernels. >> >> But a side effect of that commit is that now is not possible anymore to >> enable the EFI runtime services by default when CONFIG_PREEMPT_RT is set >> to y, even for platforms that could guarantee bounded time for EFI calls. >> >> Instead, let's add a new EFI_DISABLE_RUNTIME boolean Kconfig option, that >> would be set to n by default but to y if CONFIG_PREEMPT_RT is enabled. >> >> That way, the current behaviour is preserved but gives users a mechanism >> to enable the EFI runtimes services in their kernels if that is required. > > Is the command line switch > efi=runtime > > not working? > Yes, it is but the motivation is to be able to have EFI runtime services by default without the need for any kernel command line parameter. In the same vein, I could ask if efi=noruntime wasn't enough instead of commit ("efi: Disable runtime services on RT"). -- Best regards, Javier Martinez Canillas Linux Engineering Red Hat