Date: Sun, 2 Jun 2024 15:42:19 +0200 From: Robert Clausecker <fuz@freebsd.org> To: tuexen@freebsd.org Cc: Robert Clausecker <fuz@freebsd.org>, freebsd-riscv@freebsd.org, Mitchell Horne <mhorne@freebsd.org>, strajabot@gmail.com Subject: Re: Detecting the Zbb extension on riscv64 Message-ID: <Zlx2u52Xw7Aw6svM@fuz.su> In-Reply-To: <5343E09C-017B-40B7-9349-01F1195BBB7C@freebsd.org> References: <ZlxZn5IQuQ-zqbwl@fuz.su> <5343E09C-017B-40B7-9349-01F1195BBB7C@freebsd.org>
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Hi Michael, Am Sun, Jun 02, 2024 at 03:05:09PM +0200 schrieb tuexen@freebsd.org: > > Zbb is supported by the SiFive unmatched board for example. > just double checking: > According to > https://sifive.cdn.prismic.io/sifive/d0556df9-55c6-47a8-b0f2-4b1521546543_hifive-unmatched-datasheet.pdf > the processor supports RV64GC (RV64IMAFDC). I don't see a B there. > So does it actually support Zbb? What about Zbr? The board is based on the SiFive FU740-C000 SoC, which uses a quad-core U74 CPU. Reading the [U74 Core Complex Manual], we find that it supports the Zba and Zbb instruction set extensions. [U74 Core Complex Manual]: https://starfivetech.com/uploads/u74_core_complex_manual_21G1.pdf Though on the other hand, if I actually try to execute a program using the CTZ instruction, I get a SIGILL... what's going on here? Yours, Robert Clausecker -- () ascii ribbon campaign - for an encoding-agnostic world /\ - against html email - against proprietary attachments
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