From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D11F2E0401; Tue, 27 Jan 2026 22:42:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769553778; cv=none; b=cr/hDV31N6CYHVF478mQsChesu1BxdjTkRPp1l3dfVJZpZd1c0MkidmOF6wRnmFnOg1+vQ39tDaY1VL/XfNB5uc/6c7cNT8Kd6YXCUUkfr+IxbCyecCzXZetI0gDIbBEK92v1HmY2CuqIonQI0F8Wiv1BJXpnHTLcIn3/FSl/z8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769553778; c=relaxed/simple; bh=ezxKf+roc8CqaN3UTazwnF33h8Lc4jzlpSmlukud7i0=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=AsUlZgEWiqrQLJfGqFftjkUgM0lUybTLzs6Y7cgGaa6zGYPJ9EibTW3cB/PNDpXNA+Oq0JdutlK3wIyfvLSno++qwTRGehk6oAOCrvKFD4vx0j1pfkrwCl3DU2SHtn+p9o2yWEbXRI3V7v9fjakzFtKMYiMkzKta8l2Vo9f/vdc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=suvxqLDl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="suvxqLDl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CADF7C116C6; Tue, 27 Jan 2026 22:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769553777; bh=ezxKf+roc8CqaN3UTazwnF33h8Lc4jzlpSmlukud7i0=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=suvxqLDlrEX44Z0wh4czJeKEchpyhPar0UMrXbCp3ye7k55uCKWqbX4XaEbz+fk9t dNYOLBdm/1YSstghBcldaqi4tj44xvlpXlh8MhG//7UBZMqlQ4vi9aXearS+vhBZCC F+RngaduHMtKapuUZyAjyEatXQXKYjZpU5F5i9ifnHaFWuz70GoCZDH/rABOSmC3a8 52dX5apqUvix92NKLAmB0B0EkmdLxVFP80LpFSpaF6pgcEE9RthTkAXFhucR03KQHV AcDwpGLBTVOmbtrCCpMnOr9aqSmr5UgsoloblIlHD7Ohgc4grgmtM5AgGF7LMV0k0L /dNzaTP2TLT3A== Date: Tue, 27 Jan 2026 16:42:56 -0600 From: Bjorn Helgaas To: Ilpo =?utf-8?B?SsOkcnZpbmVu?= Cc: linux-pci@vger.kernel.org, Bjorn Helgaas , Dominik Brodowski , LKML , Simon Richter Subject: Re: [PATCH 05/23] PCI: Remove old_size limit from bridge window sizing Message-ID: <20260127224256.GA384149@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Jan 27, 2026 at 01:39:39PM +0200, Ilpo Järvinen wrote: > On Mon, 26 Jan 2026, Bjorn Helgaas wrote: > > On Mon, Jan 26, 2026 at 11:16:01AM -0600, Bjorn Helgaas wrote: > > > On Fri, Dec 19, 2025 at 07:40:18PM +0200, Ilpo Järvinen wrote: > > > > calculate_memsize() applies lower bound to the resource size before > > > > aligning the resource size making it impossible to shrink bridge window > > > > resources. I've not found any justification for this lower bound and > > > > nothing indicated it was to work around some HW issue. > ... > > > > Reported-by: Simon Richter > > > > > > I guess this report was > > > https://lore.kernel.org/r/f9a8c975-f5d3-4dd2-988e-4371a1433a60@hogyros.de/, > > > right? > > > > And this looks like a regression in v6.18 that will persist in v6.19. > > > > Is that the right thing? I wonder if we should move these first five > > patches to pci/for-linus so they land in v6.19? > > Fine with me if you want to do that. Stable people would pick things that > landing in the merge window into Linus' tree anyway so the difference > isn't going to be that huge. > > Patch 3 is the scariest of the changes and is not strictly even a fix > (without it there are two parallel alignment approaches though which > wastes some stack space). It will have some impact on resource allocation > when the new approach is enabled for everything were as previously the new > sizing/alignment approached were only used in the relative safe haven of > relaxed tail alignment cases; though in my tests, surprisingly few changes > did occur. > > The patch 4 too is on the edge, if you want to push that through for-linus > (but it's not dangerous and is useful for complex topos). > > I don't know how you are going to handle the pci/resource branch then > though as I expect the rest of the series to not apply cleanly without > those 5 patches. OK, I'll leave it as-is, with all of this on pci/resource for v6.20. I was concerned that lots of people would trip over the issue Simon reported, but I don't see many reports on the web. Bjorn