From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56187) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z0XzC-0008DW-T0 for qemu-devel@nongnu.org; Thu, 04 Jun 2015 12:27:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z0Xz8-0007At-C4 for qemu-devel@nongnu.org; Thu, 04 Jun 2015 12:27:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53830) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z0Xz8-0007Ap-5Q for qemu-devel@nongnu.org; Thu, 04 Jun 2015 12:27:14 -0400 Message-ID: <55707C5D.9060000@redhat.com> Date: Thu, 04 Jun 2015 18:27:09 +0200 From: Laszlo Ersek MIME-Version: 1.0 References: <556DC60B.20402@redhat.com> <556DD8F7.7020502@redhat.com> <556EB7B7.5030004@redhat.com> <556ED4D0.1030105@redhat.com> <556F64C1.7010406@redhat.com> <556F899A.3090905@redhat.com> <55701D92.8010408@redhat.com> <55704CCF.1050201@redhat.com> <55706C59.8000908@redhat.com> In-Reply-To: <55706C59.8000908@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC] edk2 support for a new QEMU device - PXB (PCI Expander Device) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum Cc: "Gabriel L. Somlo (GMail)" , edk2-devel@lists.sourceforge.net, qemu devel list , "Michael S. Tsirkin" On 06/04/15 17:18, Marcel Apfelbaum wrote: > On 06/04/2015 04:04 PM, Laszlo Ersek wrote: >> On 06/04/15 11:42, Marcel Apfelbaum wrote: >>> On 06/04/2015 02:11 AM, Laszlo Ersek wrote: >> >>>> What element type do you propose for the array in the new fw_cfg file? >>>> (And what name for the fw_cfg file itself?) >>>> >>>> "etc/extra-pci-roots" uses uint64_t, little endian, for the number of >>>> extra root buses. (In fact if you expose the explicit list in a >>>> separate >>>> file, then the element count is not even necessary separately, because >>>> file sizes are available in the fw_cfg directory, and I can divide the >>>> file size with the element size.) >> >>> I can prepare another file. >> >> As long as we're crossing neither a QEMU nor a SeaBIOS release boundary, >> I think we could just change the contents of the same file, with the >> existing name. > The extra-roots file was existing before PXB. > I am afraid to break some other thing. > This is why I prefer another file. Noted. >>> Regarding the new array, each element >>> should be >>> a number between 0x0 and 0xff, so a uint8_t seems fair. >> >> Hm. The number of bytes to save here is really small, and it has been >> suggested to maybe try to support segments? I don't know anything about >> PCI segments; I vaguely recall that it allows for disjoint bus >> intervals, with each interval having at most 256 elements. Maybe we >> could accommodate that with a uint32_t element type? > While I dont' really care about the type, > Pmultiple pci segments correspond to multiple *host bridges*, > as opposed to one host bridge with multiple root bridges. Noted. UINT8 is fine then. Thanks! Laszlo