From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49908) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6J7T-0000oi-Tm for qemu-devel@nongnu.org; Mon, 05 Aug 2013 07:38:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V6J7O-0000BI-0w for qemu-devel@nongnu.org; Mon, 05 Aug 2013 07:38:35 -0400 Received: from mout.web.de ([212.227.15.4]:49520) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6J7N-0000B3-N2 for qemu-devel@nongnu.org; Mon, 05 Aug 2013 07:38:29 -0400 Received: from mchn199C.mchp.siemens.de ([95.157.58.223]) by smtp.web.de (mrweb002) with ESMTPSA (Nemesis) id 0M6ml2-1U9xGY2rjg-00wXYx for ; Mon, 05 Aug 2013 13:38:28 +0200 Message-ID: <51FF8EB0.3080605@web.de> Date: Mon, 05 Aug 2013 13:38:24 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <51FCBFCD.5020608@web.de> <51FF71BD.5040400@suse.de> <51FF7ED6.3050101@web.de> <51FF8211.3050509@web.de> <51FF867E.6070906@web.de> <51FF8DE5.9010901@suse.de> In-Reply-To: <51FF8DE5.9010901@suse.de> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="WoGoQko1Ccm1k23JUBTPbINE4tmr9v7Cd" Subject: Re: [Qemu-devel] [PATCH 1/2] memory: Provide separate handling of unassigned io ports accesses List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= Cc: Peter Maydell , Alexey Kardashevskiy , qemu-devel , =?UTF-8?B?SGVydsOpIFBvdXNzaW5lYXU=?= , Paolo Bonzini , Aurelien Jarno , Richard Henderson This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --WoGoQko1Ccm1k23JUBTPbINE4tmr9v7Cd Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2013-08-05 13:35, Andreas F=C3=A4rber wrote: > Am 05.08.2013 13:03, schrieb Jan Kiszka: >> On 2013-08-05 12:51, Peter Maydell wrote: >>> On 5 August 2013 11:44, Jan Kiszka wrote: >>>> On 2013-08-05 12:36, Peter Maydell wrote: >>>>> On 5 August 2013 11:30, Jan Kiszka >>>>> wrote: >>>>>> On 2013-08-05 11:59, Peter Maydell wrote: >>>>>>> Or do you mean that if we had: >>>>>>> >>>>>>> [ system memory region, with its own default read/write >>>>>>> ops ] >>>>>> >>>>>> I cannot imagine how this could work. The system memory >>>>>> region has no clue about what the regions below it can >>>>>> handle and what not. So it has to pass through the io >>>>>> window. >>>>> >>>>> The system memory region's just a container, you can add a=20 >>>>> background region to it at lowest-possible-priority, which=20 >>>>> then takes accesses which are either (a) not in any >>>>> subregion or (b) in a subregion but that container doesn't >>>>> specify its own io ops and nothing in that container handles >>>>> the access. (Or you could create the system memory region >>>>> with its own IO ops, which would have the same effect.) >>>> >>>> First, we do not render MMIO and IO within the same address >>>> space so far. >>> >>> Is this a statement made because you've checked all the boards=20 >>> and know that nobody's mapping the system-io memory region into=20 >>> the system-memory region? (It is technically trivial, you just >>> need to call memory_region_add_subregion() directly or >>> indirectly...) >=20 >> I know this because I just recently wrote the patch that enables >> this trivial step, i.e. converted PIO dispatching to the memory >> subsystem. >=20 > Several patches have been applied since, e.g. >=20 > sPAPR PHB: > http://git.qemu.org/?p=3Dqemu.git;a=3Dcommit;h=3D66aab867cedd2a2d81b4d6= 4eff7c3e0f6f272bbf > -> aliases system_io() >=20 > PReP i82378 PCI-ISA bridge: > http://git.qemu.org/?p=3Dqemu.git;a=3Dcommit;h=3D5c9736789b79ea49cd236a= c326f0a414f63b1015 > -> uses pci_address_space_io() >=20 > Alpha Typhoon: > http://git.qemu.org/?p=3Dqemu.git;a=3Dcommit;h=3D056e6bae1c91f47165d962= 564f82f5176bae47f0 > http://git.qemu.org/?p=3Dqemu.git;a=3Dcommit;h=3D3661049fec64ffd7ab008e= 57e396881c6a4b53a4 >=20 > [For those joining late, this discussion is about whether making PIO > MemoryRegion ..._io rather than just container might hurt some use > case. If you have a concrete test case that would be appreciated; a > we-don't-care-about-such-a-fringe-case would help as well.] OK, one assumption became outdated, but the other will remain true once the patch is applied. So let's close this discussion. Jan --WoGoQko1Ccm1k23JUBTPbINE4tmr9v7Cd Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlH/jrEACgkQitSsb3rl5xQbHQCgvi2xfxDj7Jf2GNzPQBrCG29C lcMAnA7qlnbeA1wyUUKwFYyFkwJ1hX5n =BYqi -----END PGP SIGNATURE----- --WoGoQko1Ccm1k23JUBTPbINE4tmr9v7Cd--