From: Dave Hansen <dave.hansen@intel.com>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Charlie Jenkins <charlie@rivosinc.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Richard Henderson <richard.henderson@linaro.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@kernel.org>,
Russell King <linux@armlinux.org.uk>, Guo Ren <guoren@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Helge Deller <deller@gmx.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Naveen N Rao <naveen@kernel.org>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
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Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
"David S. Miller" <davem@davemloft.net>,
Andreas Larsson <andreas@gaisler.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
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Peter Zijlstra <peterz@infradead.org>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Shuah Khan <shuah@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org,
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loongarch@lists.linux.dev, linux-mips@vger.kernel.org,
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sparclinux@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH RFC v2 0/4] mm: Introduce MAP_BELOW_HINT
Date: Fri, 30 Aug 2024 08:03:25 -0700 [thread overview]
Message-ID: <a922737b-be1a-4ae9-b2d8-fefc44bb6419@intel.com> (raw)
In-Reply-To: <ab90ff3b-67dc-4195-89a7-54e394da1aa0@lucifer.local>
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.
next prev parent reply other threads:[~2024-08-30 15:03 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-29 7:15 Charlie Jenkins
2024-08-29 7:15 ` [PATCH RFC v2 1/4] mm: Add MAP_BELOW_HINT Charlie Jenkins
2024-08-29 8:26 ` Michael Ellerman
2024-08-30 1:16 ` Charlie Jenkins
2024-08-29 7:15 ` [PATCH RFC v2 2/4] mm: Add hint and mmap_flags to struct vm_unmapped_area_info Charlie Jenkins
2024-08-29 8:48 ` Lorenzo Stoakes
2024-08-30 1:11 ` Charlie Jenkins
2024-09-03 17:18 ` Christophe Leroy
2024-08-29 7:16 ` [PATCH RFC v2 3/4] mm: Support MAP_BELOW_HINT in vm_unmapped_area() Charlie Jenkins
2024-08-29 7:16 ` [PATCH RFC v2 4/4] selftests/mm: Create MAP_BELOW_HINT test Charlie Jenkins
2024-08-29 8:30 ` [PATCH RFC v2 0/4] mm: Introduce MAP_BELOW_HINT Michal Hocko
2024-08-29 17:33 ` Charlie Jenkins
2024-09-03 8:44 ` Michal Hocko
2024-08-29 8:42 ` Lorenzo Stoakes
2024-08-29 9:54 ` Lorenzo Stoakes
2024-08-29 22:16 ` Charlie Jenkins
2024-08-30 9:52 ` Lorenzo Stoakes
2024-08-31 1:45 ` Charlie Jenkins
2024-08-30 15:03 ` Dave Hansen [this message]
2024-08-30 15:18 ` Lorenzo Stoakes
2024-08-29 9:02 ` Vlastimil Babka
2024-08-29 17:00 ` Palmer Dabbelt
2024-09-05 6:47 ` Kirill A. Shutemov
2024-09-05 17:26 ` Charlie Jenkins
2024-09-09 9:46 ` Kirill A. Shutemov
2024-10-21 13:22 ` Steven Price
2024-10-21 19:48 ` Liam R. Howlett
2024-10-23 9:31 ` Steven Price
2024-10-23 18:10 ` Liam R. Howlett
2024-10-24 10:52 ` Steven Price
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