From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B006AC982C3 for ; Wed, 16 Sep 2026 14:30:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=nRPwui//DdZeQJe3FFPtKCePfUSwnp41dl+UxM2JXEA=; b=Po9fUfQQ+HTbJsQ2t/4/uMiU6C fnCxEZn7rKpHr47tLn+dFOyXbDAw9ze11Bmgxds8AxDoTeUcaW6iR128ZvnXiJcyTDA5Rmw7N5yt4 V9qsTPvfUBT07ag7nvMcfunwQnqGCTAEiwN+jzTn0cZaOQ+XIYn3WQbuyFdrS6A8LoUTf/RRjVeqN C8rh1ClzA5z+VbKSg6GbZ/NEvPqFJ6CrHuffgnnxTF2Fc8DcE1tzVvGmmFehWrY+g1sf060oFYQXi QJLHepW6OvqH/iSWKqoQGJJhWjiYCKs6Ww3KJ1PoxqVP47qavA1zNnMgV3W5N1tPotr1Jc//IKXr4 8gLS4JKQ==; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/7/26 05:50, Anshuman Khandual wrote: > FEAT_D128 halves PTRS_PER_PXX thus shrinking the VA range coverage > for each page table level. Hence in order to preserve all existing > VA range configurations, some geometry now need to become 5-level. > Hmm, wasn't this 5-levels before, but other code allocated+initialized the p4d table for us? I mean, I see how we are filling in another level, but I don't see how we would reconfigure something to use 5 page table levels? > Since fixmap is used to build and manipulate page tables early on > during boot the mapping must also gain that additional level which > was not required earlier. I am no expert ... but I am confused :) We do have a loop only in early_fixmap_init_pmd(). So we cannot possibly span more than a single ... PTE table? > > Enable fixmap with 5 level page table when required. This creates table > entries at the PGD level. Add a fallback stub for pgd_page_paddr() when > (PGTBALE_LEVELS <= 4) which helps in intercepting any unintended usage. Again, I am very confused. Is it really just "As the page table layout changes, we might no longer have a p4d table pre-populated for the range our fixmap falls into. So if there is no p4d table yet, populate a static one just like we do for the other levels." -- Cheers, David