From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=209.132.183.28; helo=mx1.redhat.com; envelope-from=lersek@redhat.com; receiver=edk2-devel@lists.01.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id A26B9211D67E4 for ; Thu, 21 Mar 2019 12:04:24 -0700 (PDT) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 262E17E427; Thu, 21 Mar 2019 19:04:24 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-120-143.rdu2.redhat.com [10.10.120.143]) by smtp.corp.redhat.com (Postfix) with ESMTP id DC96310018FB; Thu, 21 Mar 2019 19:03:51 +0000 (UTC) To: Ard Biesheuvel , "Wu, Hao A" Cc: "edk2-devel@lists.01.org" , "Justen, Jordan L" , "Ni, Ray" References: <20190315071603.16936-1-hao.a.wu@intel.com> <2cef7754-a5ab-274e-44ab-14ba092f7d40@redhat.com> From: Laszlo Ersek Message-ID: <8aecf13a-97d9-357d-b343-094f95f36f86@redhat.com> Date: Thu, 21 Mar 2019 20:03:50 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 21 Mar 2019 19:04:24 +0000 (UTC) Subject: Re: [PATCH v1 0/2] Ovmf: Stop using ISA drivers within IntelFrameworkModulePkg X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Mar 2019 19:04:24 -0000 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 03/21/19 11:08, Ard Biesheuvel wrote: > On Thu, 21 Mar 2019 at 07:44, Wu, Hao A wrote: >> >>>>> >>>>> Just a couple of notes from my side - I'm sure Laszlo will have a much >>>>> longer list :-) >>>>> >>>>> - Dropping the floppy driver is fine with me. >>>>> - What is OVMF specific about this driver? Is it only the hardcoded >>>>> list of COM1/COM2/PS2 keyboard? If so, should we split this into a >>>>> driver and a library class, where the driver lives in MdeModulePkg, >>>>> and the library is implemented in the context of OVMF? >>>> >>>> Hello Ard, >>>> >>>> I think the special thing for this one is that: >>>> For QEMU, it does not have a Super I/O (SIO) chip. While, as far as I >>>> know, the SIO chip exists on other platforms. The driver proposed here >>>> simulates the behavior of an SIO chip. IMO, if we find more platforms that >>>> do not have a SIO chip, we can convert the driver into a general one. >>>> >>>> Also, for the implementation of the services in the Super I/O protocol, >>>> the proposed driver just does the minimal effort in order to support the >>>> serial/PS2 keyboard. >>> >>> Here's why I'd like the majority of this driver to live under >>> MdeModulePkg (for example through a lib class separation like Ard suggests): >>> >>> Because then its maintenance would not be the responsibility of OvmfPkg >>> maintainers. >>> >>> Consider, this driver is absolutely huge (1.5-2 kLOC), for doing "the >>> minimal effort in order to support the serial/PS2 keyboard". >>> >>> The risk of regressions is extreme (the PS/2 keyboard is the default >>> one, and if it breaks *subtly*, almost all users will be inconvenienced, >>> but not necessarily soon enough for us to get reports about it *early* >>> in the current development cycle). >>> >>> I realize that IntelFrameworkModulePkg/Bus/Isa/* drivers are frowned >>> upon nowadays, they may be ugly / platform specific / etc etc etc, but >>> they have also proved themselves to *work*, and (as far as I remember) >>> they have required practically zero fixes in order to function well on QEMU. >>> >>> It is very unwelcome by me to take on the maintenance burden for a >>> driver that is all of: >>> - not widely tested, >>> - replacing a proven set of drivers that is critical to users, >>> - large. >>> >>> I understand that Intel wants to stop maintaining >>> IntelFrameworkModulePkg/Bus/Isa/*, but the above price is too high for me. >>> >>> Compare the case if we simply moved the >>> IntelFrameworkModulePkg/Bus/Isa/* drivers under OvmfPkg: >>> - still large, >>> - but widely tested (with minimal churn in the past), >>> - and no risk of regressions. >>> >>> So in this form, I'm generally opposed to the switch. The two sets of >>> drivers need to coexist for a while, and we must expose the new drivers >>> to users while providing them with some sort of easy fallback. (I'd >>> prefer that fallback to be dynamically configurable, but, again, if your >>> keyboard breaks, how do you interact with e.g. the UEFI shell? So I >>> guess a static build flag would do as well.) I think the old drivers >> >> Hello Laszlo, >> >> I agree with your point. So your suggestion is to: >> >> 1. Duplicate the below drivers into OvmfPkg: >> PcAtChipsetPkg/IsaAcpiDxe/IsaAcpi.inf >> IntelFrameworkModulePkg/Bus/Isa/IsaBusDxe/IsaBusDxe.inf >> IntelFrameworkModulePkg/Bus/Isa/IsaSerialDxe/IsaSerialDxe.inf >> IntelFrameworkModulePkg/Bus/Isa/Ps2KeyboardDxe/Ps2keyboardDxe.inf >> >> 2. Meanwhile, add the proposed SioBusDxe driver in the OvmfPkg as well >> >> 3. Add a static build flag within OvmfPkg to let users choose between: >> a) New OVMF SioBusDxe driver + ISA device drivers under >> MdeModulePkg/Bus/Isa; >> b) Legacy ISA stack copied from PcAtChipsetPkg & IntelFrameworkModulePkg >> >> Is my understanding correct? Yes (but see below, at the end). >>> should be removed only in the edk2 stable tag that comes *after* the >>> next one, once we've given the drivers enough time to "prove themselves". >> >> Do you mean we should keep the copy of the legacy ISA stack from >> PcAtChipsetPkg & IntelFrameworkModulePkg until the announcement of >> edk2-stable201905 tag? Yes, exactly. People that adopt "edk2-stable201905" should be able to switch back to the old driver stack. NB: I certainly agree that the new code should be made the *default*. >> > > I think we should just keep the IntelFrameworkModulePkg components in > place until we are ready to stop using them in OVMF. Cloning them into > OvmfPkg now just so we can remove IntelFrameworkModulePkg in its > entirety has little added value IMO. I fully agree with this modification (it minimizes the churn), but I'm unsure how quickly Intel would like to rid themselves of IntelFrameworkModulePkg. If their deadline is edk2-stable201905, then that conflicts with my request above, and we might have no choice in moving the code to OvmfPkg, for the sake of one more stable tag. Thanks Laszlo