From: Richard Henderson <richard.henderson@linaro.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~
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next prev parent reply other threads:[~2023-01-11 5:23 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1631497278-29829-1-git-send-email-vincent.chen@sifive.com>
[not found] ` <1631497278-29829-3-git-send-email-vincent.chen@sifive.com>
[not found] ` <871r5sd1zq.fsf@oldenburg.str.redhat.com>
[not found] ` <20210913135247.GL13220@brightrain.aerifal.cx>
[not found] ` <CABvJ_xjGZ3S0oAkT08x4DToQFdcUH06omk2OTT1EHDZRJ-2wKg@mail.gmail.com>
[not found] ` <87sfy5ndid.fsf@oldenburg.str.redhat.com>
[not found] ` <CABvJ_xjSREsdemJkCJMGSx+09jrNoSbXCwuxF0zEQmZtHrWMvg@mail.gmail.com>
[not found] ` <d613968f-0fae-1994-3bee-fb10765167c3@rivosinc.com>
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
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
2023-01-11 4:28 ` Jeff Law
2023-01-11 4:57 ` Richard Henderson
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
2023-01-23 13:29 ` Andy Chiu
2023-01-11 5:05 ` Anup Patel
2023-01-11 5:23 ` Richard Henderson [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
2022-12-22 23:47 ` Conor Dooley
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
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