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[2001:1c00:c1e:bf00:1054:9d19:e0f0:8214]) by smtp.gmail.com with ESMTPSA id p7sm1651715edr.6.2021.10.14.01.15.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Oct 2021 01:15:14 -0700 (PDT) Subject: Re: [PATCH v2] x86/PCI: Ignore E820 reservations for bridge windows on newer systems To: =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= Cc: "Rafael J . Wysocki" , Mika Westerberg , Bjorn Helgaas , Myron Stowe , Juha-Pekka Heikkila , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , linux-pci@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Benoit_Gr=c3=a9goire?= , Hui Wang References: <20211011090531.244762-1-hdegoede@redhat.com> From: Hans de Goede Message-ID: <10ae4edf-277c-41cf-020a-56406213a3f4@redhat.com> Date: Thu, 14 Oct 2021 10:15:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi Krzysztof, On 10/14/21 12:13 AM, Krzysztof Wilczyński wrote: > Hi Hans, > > Thank you for sending the patch over! > > [...] >> [ 0.000000] BIOS-e820: [mem 0x000000004bc50000-0x00000000cfffffff] reserved >> [ 0.557473] pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] > > A very small nitpick: we usually remove time/date stamps from kernel ring > buffer outputs keeping only the relevant message parts left. Ok, I'll do a v3 fixing this. > > [...] >> Old systems are defined here as BIOS year < 2018, this was chosen to >> make sure that pci_use_e820 will not be set on the currently affected >> systems, while at the same time also taking into account that the >> systems for which the E820 checking was orignally added may have > > A tiny typo of "originally" in the sentence above. And this. > [...] >> @@ -232,3 +236,9 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val) >> # define x86_default_pci_init_irq NULL >> # define x86_default_pci_fixup_irqs NULL >> #endif >> + >> +#if defined CONFIG_PCI && defined CONFIG_ACPI > > I know that Mika already asked about this, and you responded, so I can only > added: brackets, let's add brackets, most definitely. :) I've no big preference either way, so I'll move to using parentheses for the next version. > > [...] >> +/* Consumed in arch/x86/kernel/resource.c */ >> +bool pci_use_e820 = false; > > A small nitpick: not sure if this comment is needed as probably most people > working with this code would use "git grep" and likes to list occurrences > where the variables is used. But, this is highly subjective, thus there is > probably nothing to change here. I put it the comment there because the other use_foo flag directly above it are all static, so it is there to explain why this one is not static. At least that was my idea behind the comment :) > >> + printk(KERN_INFO "PCI: %s E820 reservations for host bridge windows\n", >> + pci_use_e820 ? "Honoring" : "Ignoring"); > > I know you followed the existing style, which is very much appreciated, but > if and where possible, we should move to newer API/style and replace the > printk() above with pr_info(). New code should not be adding old style if > it can be helped (checkpatch.pl would warn about this too). What do yo you > think? Yes checkpatch complained about this, still I deliberately ignored that, as you said I'm following the existing style here. I very much dislike mixing styles in a single file. If we want to change this for this file then IMHO the right thing to do would be a follow up patch changing all the printk-s at once. Regards, Hans