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[2001:1c00:c0c:fe00:fc7e:fd47:85c1:1ab3]) by smtp.gmail.com with ESMTPSA id k133sm12979071wma.11.2020.03.12.07.05.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Mar 2020 07:05:39 -0700 (PDT) Subject: Re: [tip: irq/core] x86: Select HARDIRQS_SW_RESEND on x86 To: Linus Walleij Cc: "linux-kernel@vger.kernel.org" , linux-tip-commits@vger.kernel.org, Thomas Gleixner , x86 References: <20200123210242.53367-1-hdegoede@redhat.com> <158396292503.28353.1070405680109587154.tip-bot2@tip-bot2> <1cb0397f-e583-3d7e-dff3-2cc916219846@redhat.com> From: Hans de Goede Message-ID: <231875e7-fc72-edb4-a4de-fc7cfc3cdca3@redhat.com> Date: Thu, 12 Mar 2020 15:05:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 3/12/20 3:02 PM, Linus Walleij wrote: > On Thu, Mar 12, 2020 at 2:49 PM Hans de Goede wrote: > > [Me] >>> I see that ARM and ARM64 simply just select this. What >>> happens if you do that and why is x86 not selecting it in general? >> >> Erm, "selecting it in general" (well at least on x86) is what >> this patch is doing. > > Sorry that I was unclear, what I meant to say is why wasn't > this done ages ago since so many important architectures seem > to have it enabled by default. > > I suppose the reason would be something like "firmware/BIOS > should handle that for us" and recently that has started to > break apart and x86 platforms started to be more like ARM? That (x86 becoming more like ARM, sorta, kinda) as well as that turning it on on x86 was not safe until Thomas wrote the 2 patches which are marked as dependencies in the commit message for this patch. Regards, Hans