Date: Mon, 17 Dec 2018 14:51:48 +0100 From: Alexander Lochmann <alexander.lochmann@tu-dortmund.de> To: freebsd-stable@freebsd.org Cc: Horst Schirmeier <horst.schirmeier@tu-dortmund.de> Subject: Address Collision using i386 4G/4G Memory Split Message-ID: <38ad0d50-c776-9deb-d56b-db8db548cefc@tu-dortmund.de>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --7lBJymOEjXxY4qO0tcBbAHav0BU0zg5Rv Content-Type: multipart/mixed; boundary="vfYBy8ekYmh25Ls8CxdwWuN07ecgrYvo9"; protected-headers="v1" From: Alexander Lochmann <alexander.lochmann@tu-dortmund.de> To: freebsd-stable@freebsd.org Cc: Horst Schirmeier <horst.schirmeier@tu-dortmund.de> Message-ID: <38ad0d50-c776-9deb-d56b-db8db548cefc@tu-dortmund.de> Subject: Address Collision using i386 4G/4G Memory Split --vfYBy8ekYmh25Ls8CxdwWuN07ecgrYvo9 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi folks! According to git commit e3089a (https://reviews.freebsd.org/D1463) FreeBSD 12.0 i386 uses separate address spaces for kernel and user space. So basically two memory areas, one in each space, can have the same address. Is this possible with FreeBSD 12.0? Is this likely to happen? On my opinion, this is also very expensive in terms of performance. Any copy{in,out} has to flush the TLB. (http://fxr.watson.org/fxr/source/i386/i386/copyout_fast.s#L91) Why are you still using this 4G/4G approach? Regards, Alex --=20 Technische Universit=C3=A4t Dortmund Alexander Lochmann PGP key: 0xBC3EF6FD Otto-Hahn-Str. 16 phone: +49.231.7556141 D-44227 Dortmund fax: +49.231.7556116 http://ess.cs.tu-dortmund.de/Staff/al --vfYBy8ekYmh25Ls8CxdwWuN07ecgrYvo9-- --7lBJymOEjXxY4qO0tcBbAHav0BU0zg5Rv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEElhZsUHzVP0dbkjCRWT7tBbw+9v0FAlwXqfQACgkQWT7tBbw+ 9v3JbA//en3ytdOxukhGNNL5xTITaUp1wuAeq4ncgqPfuFA1Ttwufug60Q/WozWj ynm2/iy1oILg9IhIKmV8SYOzKRJwCFDWIV1sQB9vgaNdyGxlgpiXTXxAR1t6w5mI +wIPxVtVHVZXkCLsIV+ZXIqzfsEj5qhDAhW+ZhKdueQFwZl7ykNeJaEUrH8gaqYg AlOnNY2YAciD3cvq44jQZPNdRT/xG9q9gZxKFgj0X6Ph183VjIRF2RjYDlR0TyR/ Kx+qZI/CYSkK3Mwu5RvuK0wjgJT5qCjFovqYRNOr6EteVytO4FxM/iMdC1uRpOb+ LYFXiOuNQSUcDpfa0F1977MnHK78druNoF0zIJ6dOanRPPSo/thzQl+j4VThIJ4C dqKBdSeF/LH/uLVFQhUqagzYADdFpyqVRcSBwmBQ8ien2LqAWmhsWI/cu8b2b17d hvwPgRa4MIo/I5MlfQvkGRguv47wBvzyHtIs7TBnfGqubfXJpYYIWxNXg3BftB+1 qxtNs0+AM3/6fykgw6uGZrXQx1wdUP73U3BcVnUxj8AbBXACZdizt+bdt4xXNa4a Drop/+9XE0WccaiPctTADIZWra/E0fiCODA7ZAySx7Cm/58Cu2GcgG1iooE0H3hW FWw+u5IiXTqr6hmZkECI2pGFZV7xDFJ0I0TFFKefrS58kx3NOQ4= =c8pg -----END PGP SIGNATURE----- --7lBJymOEjXxY4qO0tcBbAHav0BU0zg5Rv--
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