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Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S. Miller" , Andreas Larsson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Muchun Song , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Shuah Khan , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "Kirill A. Shutemov" References: <20240829-patches-below_hint_mmap-v2-0-638a28d9eae0@rivosinc.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 74747140025 X-Rspamd-Server: rspam01 X-Stat-Signature: mwxg14am67b6hxgobtw8x69d3zmrtcpq X-HE-Tag: 1725030223-343869 X-HE-Meta: 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 XTW2NZW7 TTKCokdhUFfxv56uU4xxoV8h122xQVGKFxv/buez4mJxi9ucVpOOQFvekujfRXvWOAnTXC2hReTTo27YGmFZBECSgVo/bjy6ajEfXEZXbhaDvOIF41Q7JIPOAqzfQPFTtL3R3ybo38pAUaNNs1bny4SANUn7t3K2AAw0G8Dqx9kh6EOg01ePrzI0Xh+JGXJArEW9eks0ojMR9q/+1hZjvwt3GDDtv4AN8/I+fkdhSPN+roq7oMCrfuH3/sFE6O5pvT0c2Myqv8R24haWNVcT18z847Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/29/24 01:42, Lorenzo Stoakes wrote: >> These applications work on x86 because x86 does an implicit 47-bit >> restriction of mmap() address that contain a hint address that is less >> than 48 bits. > You mean x86 _has_ to limit to physically available bits in a canonical > format 🙂 this will not be the case for 5-page table levels though... By "physically available bits" are you referring to the bits that can be used as a part of the virtual address? "Physically" may not have been the best choice of words. ;) There's a canonical hole in 4-level paging and 5-level paging on x86. The 5-level canonical hole is just smaller. Also, I should probably say that the >47-bit mmap() access hint was more of a crutch than something that we wanted to make ABI forever. We knew that high addresses might break some apps and we hoped that the list of things it would break would go down over time so that we could eventually just let mmap() access the whole address space by default. That optimism may have been misplaced.