From: Richard Henderson via Libc-alpha <libc-alpha@sourceware.org>
To: Vineet Gupta <vineetg@rivosinc.com>, Kito Cheng <kito.cheng@sifive.com>
Cc: "Philipp Tomsich" <philipp.tomsich@vrull.eu>,
"Andy Chiu" <andy.chiu@sifive.com>,
"Vincent Chen" <vincent.chen@sifive.com>,
"Florian Weimer" <fweimer@redhat.com>,
"Rich Felker" <dalias@libc.org>,
"Andrew Waterman" <andrew@sifive.com>,
"Palmer Dabbelt" <palmer@rivosinc.com>,
"Christoph Müllner" <christoph.muellner@vrull.eu>,
davidlt@rivosinc.com, "Arnd Bergmann" <arnd@arndb.de>,
"Björn Töpel" <bjorn@kernel.org>,
"Szabolcs Nagy" <szabolcs.nagy@arm.com>,
"Greentime Hu" <greentime.hu@sifive.com>,
"Aaron Durbin" <adurbin@rivosinc.com>,
"Andrew de los Reyes" <adlr@rivosinc.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
"GNU C Library" <libc-alpha@sourceware.org>
Subject: Re: Auto-enabling V unit and/or use of elf attributes (was Re: Adding V-ext regs to signal context w/o expanding kernel struct sigcontext to avoid glibc ABI break)
Date: Tue, 10 Jan 2023 21:23:26 -0800 [thread overview]
Message-ID: <b34f9455-e89b-4972-0913-2ab307843f3c@linaro.org> (raw)
In-Reply-To: <3923eeee-e4dc-0911-40bf-84c34aee962d@linaro.org>
On 1/10/23 17:22, Richard Henderson wrote:
> And, surely, there's some minimal vector configuration for which the allocation must succeed.
To answer my own question here, no, there does not seem to be a way to cap VLMAX in the OS
or the hypervisor -- vsetvli rd, r0, e8 will always set VL to the VLMAX for which the cpu
is configured.
(ARM SVE can artificially limit the vector length. Linux chooses the default vector
length so that state fits within the existing 4k signal stack frame. This is good enough
for the vector usage within e.g. strlen. In order to take advantage of any larger vector
length the hardware may support, one must use a prctl.)
r~
next prev parent reply other threads:[~2023-01-11 5:23 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 1:41 [RFC patch 0/5] RISC-V: Add vector ISA support Vincent Chen
2021-09-13 1:41 ` [RFC patch 1/5] RISC-V: Remove riscv-specific sigcontext.h Vincent Chen
2021-09-13 1:41 ` [RFC patch 2/5] RISC-V: Reserve about 5K space in mcontext_t to support future ISA expansion Vincent Chen
2021-09-13 13:44 ` Florian Weimer via Libc-alpha
2021-09-13 13:52 ` Rich Felker
2021-09-16 8:02 ` Vincent Chen
2021-09-16 8:14 ` Florian Weimer via Libc-alpha
2021-09-18 3:04 ` Vincent Chen
2022-12-09 3:39 ` RISCV kernel struct sigcontext expansion for V regs and potential glibc ABI break (was Re: [RFC patch 2/5] RISC-V: Reserve about 5K space in mcontext_t to support future ISA expansion.) Vineet Gupta
2022-12-09 4:03 ` Vineet Gupta
2022-12-20 20:05 ` Adding V-ext regs to signal context w/o expanding kernel struct sigcontext to avoid glibc ABI break Vineet Gupta
2022-12-21 15:53 ` Vincent Chen
2022-12-21 19:45 ` Vineet Gupta
2022-12-21 19:52 ` Vineet Gupta
2022-12-22 3:37 ` Vincent Chen
2022-12-22 19:25 ` Vineet Gupta
2022-12-23 2:27 ` Vincent Chen
2022-12-23 19:42 ` Vineet Gupta
2022-12-22 5:32 ` Richard Henderson via Libc-alpha
2022-12-22 18:33 ` Andy Chiu
2022-12-22 20:27 ` Vineet Gupta
2022-12-28 10:53 ` Andy Chiu
2023-01-03 19:17 ` Vineet Gupta
2023-01-04 16:34 ` Andy Chiu
2023-01-04 20:46 ` Vineet Gupta
2023-01-04 21:29 ` Philipp Tomsich
2023-01-04 21:37 ` Andrew Waterman
2023-01-04 22:43 ` Vineet Gupta
2023-01-09 13:33 ` Kito Cheng
2023-01-09 19:16 ` Vineet Gupta
2023-01-10 13:21 ` Kito Cheng
2023-01-10 18:07 ` Auto-enabling V unit and/or use of elf attributes (was Re: Adding V-ext regs to signal context w/o expanding kernel struct sigcontext to avoid glibc ABI break) Vineet Gupta
2023-01-11 1:22 ` Richard Henderson via Libc-alpha
2023-01-11 4:28 ` Jeff Law
2023-01-11 4:57 ` Richard Henderson via Libc-alpha
2023-01-11 5:07 ` Jeff Law
2023-01-11 6:00 ` Andy Chiu
2023-01-11 6:20 ` Jeff Law
2023-01-11 9:28 ` Andy Chiu
2023-01-11 12:13 ` Andy Chiu
2023-01-23 12:17 ` Conor Dooley via Libc-alpha
2023-01-23 13:29 ` Andy Chiu
2023-01-11 5:05 ` Anup Patel
2023-01-11 5:23 ` Richard Henderson via Libc-alpha [this message]
2022-12-22 22:33 ` Adding V-ext regs to signal context w/o expanding kernel struct sigcontext to avoid glibc ABI break Richard Henderson via Libc-alpha
2022-12-22 23:47 ` Conor Dooley via Libc-alpha
2022-12-22 23:58 ` Vineet Gupta
2022-12-22 20:30 ` Vineet Gupta
2022-12-22 21:38 ` Andrew Waterman
2022-12-22 1:50 ` Vincent Chen
2022-12-22 5:34 ` Richard Henderson via Libc-alpha
2021-09-16 23:56 ` [RFC patch 2/5] RISC-V: Reserve about 5K space in mcontext_t to support future ISA expansion Ben Woodard via Libc-alpha
2021-09-18 3:15 ` Vincent Chen
2021-09-20 16:41 ` DJ Delorie via Libc-alpha
2021-09-20 17:10 ` Florian Weimer via Libc-alpha
2021-10-01 1:43 ` Vincent Chen
2021-10-01 12:08 ` Adhemerval Zanella via Libc-alpha
2021-09-17 17:03 ` Rich Felker
2021-09-18 3:19 ` Vincent Chen
2021-09-13 1:41 ` [RFC patch 3/5] RISC-V: Save and restore VCSR when doing user context switch Vincent Chen
2021-09-14 23:48 ` Joseph Myers
2021-09-15 0:13 ` Andrew Waterman
2021-09-16 9:20 ` Vincent Chen
2021-10-01 13:04 ` Adhemerval Zanella via Libc-alpha
2021-09-13 1:41 ` [RFC patch 4/5] RISC-V: Extend MINSIGSTKSZ and SIGSTKSZ to backup RVV registers Vincent Chen
2021-09-13 13:51 ` Rich Felker
2021-09-16 9:25 ` Vincent Chen
2021-09-13 1:41 ` [RFC 5/5] RISC-V: Expand PTHREAD_STACK_MIN to support RVV environment Vincent Chen
2021-09-14 23:43 ` Joseph Myers
2021-09-15 10:42 ` Florian Weimer via Libc-alpha
2021-09-15 14:31 ` H.J. Lu via Libc-alpha
2021-09-16 10:21 ` Vincent Chen
2021-09-13 19:11 ` [RFC patch 0/5] RISC-V: Add vector ISA support Vineet Gupta via Libc-alpha
2021-09-15 19:37 ` Jim Wilson
2021-11-09 19:21 ` Darius Rad
2021-11-09 19:30 ` Andrew Waterman
2021-11-09 22:03 ` Darius Rad
2021-11-09 22:18 ` Andrew Waterman
2021-11-10 11:39 ` Darius Rad
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