From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55983) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9i3k-0001pL-O7 for qemu-devel@nongnu.org; Wed, 23 Nov 2016 19:38:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9i3h-00065A-JP for qemu-devel@nongnu.org; Wed, 23 Nov 2016 19:38:40 -0500 Received: from mail-qk0-x243.google.com ([2607:f8b0:400d:c09::243]:32981) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1c9i3h-00063X-Dn for qemu-devel@nongnu.org; Wed, 23 Nov 2016 19:38:37 -0500 Received: by mail-qk0-x243.google.com with SMTP id x190so2144776qkb.0 for ; Wed, 23 Nov 2016 16:38:37 -0800 (PST) Date: Wed, 23 Nov 2016 19:38:35 -0500 From: Kevin O'Connor Message-ID: <20161124003835.GA20281@morn.lan> References: <20161118103659.10448-1-lersek@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laszlo Ersek Cc: Paolo Bonzini , qemu devel list , "Michael S. Tsirkin" , Gerd Hoffmann , Igor Mammedov , "Jordan Justen (Intel address)" , Michael Kinney On Thu, Nov 24, 2016 at 01:01:58AM +0100, Laszlo Ersek wrote: > CC Jordan & Mike > > On 11/23/16 23:35, Paolo Bonzini wrote: > > > > > > On 18/11/2016 11:36, Laszlo Ersek wrote: > >> This is v3 of the series, with updates based on the v2 discussion: > >> . > >> > >> I've added feature negotiation via the APM_STS ("scratchpad") register. > >> A new spec file called "docs/specs/q35-apm-sts.txt" is included. > >> > >> Tested with new OVMF patches (about to send out those as well). > >> Regression tested with SeaBIOS (beyond simple functional tests with > >> maximum SeaBIOS logging enabled, I used gdb to step through the new > >> ich9_apm_status_changed() callback to see if it was behaving compatibly > >> with SeaBIOS). > >> > >> The series was developed and tested on top of v2.7.0, because v2.8.0-rc0 > >> crashes very quickly for me when running OVMF: > >> > >> kvm_io_ioeventfd_add: error adding ioeventfd: File exists > >> > >> It is my understanding that there are patches on the list for this: > >> > >> [Qemu-devel] [PATCH v2 for-2.8 0/3] virtio fixes > >> > >> Anyway, the series rebases to v2.8.0-rc0 without as much as context > >> differences. > > > > Hi Laszlo, > > > > sorry for the slightly delayed reply. > > > > First of all, I'm wondering if we would be better off adding a new port > > 0xB1 that is QEMU-specific, instead of reusing 0xB3. > > Sure, I can look into that, if we agree that's the best way to proceed, > for now. (Although I'm not really happy about the new memory region > stuff it would require. :() > > I CC'd Kevin to learn if he foresaw other uses for the APM_STS register > in SeaBIOS. I don't foresee further use of APM_STS in SeaBIOS. The SMM code in SeaBIOS is specific to QEMU anyway. Also, the current use of APM_STS is so trivial, we could easily remove it from SeaBIOS in a future release (were that desirable). As a general comment - it does seem unfortunate that we keep building adhoc interfaces to communicate information from firmware to QEMU. We have a generic mechanism (fw_cfg) for passing adhoc information from QEMU to the firmware, but the inverse seems to always involve magic pci registers, magic io space registers, specific init ordering, etc. That said, I don't object to your proposal. -Kevin