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From: Conor Dooley <conor@kernel.org>
To: Charlie Jenkins <charlie@rivosinc.com>
Cc: "Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Guo Ren" <guoren@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Chen-Yu Tsai" <wens@csie.org>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Samuel Holland" <samuel@sholland.org>,
	"Conor Dooley" <conor.dooley@microchip.com>,
	"Evan Green" <evan@rivosinc.com>,
	"Clément Léger" <cleger@rivosinc.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Shuah Khan" <shuah@kernel.org>,
	linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Palmer Dabbelt" <palmer@rivosinc.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-doc@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 08/17] riscv: Introduce vendor variants of extension helpers
Date: Fri, 26 Apr 2024 21:37:33 +0100	[thread overview]
Message-ID: <20240426-suitable-unsheathe-0c5f5851c891@spud> (raw)
In-Reply-To: <ZiwIBmlaDbYdmv8f@ghost>

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On Fri, Apr 26, 2024 at 01:01:10PM -0700, Charlie Jenkins wrote:
> On Fri, Apr 26, 2024 at 05:19:59PM +0100, Conor Dooley wrote:
> > On Sat, Apr 20, 2024 at 06:04:40PM -0700, Charlie Jenkins wrote:
> > > @@ -163,6 +164,8 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
> > >  	for (alt = begin; alt < end; alt++) {
> > >  		if (alt->vendor_id != THEAD_VENDOR_ID)
> > >  			continue;
> > > +		if (alt->patch_id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE)
> > > +			continue;
> > 
> > >  		if (alt->patch_id >= ERRATA_THEAD_NUMBER)
> > 
> > This number is 2, how does the patching actually work for vendor stuff
> > when the base is always greater than 2?
> > 
> 
> Patching is handled through the patcher at the end of cpufeature.c. The
> vendor_id field is set in the alternatives for errata and now also for
> vendor extensions. The vendor extension patching is all handled
> generically.
> 
> This is distinguished by the patch_id being greater than
> RISCV_VENDOR_EXT_ALTERNATIVES_BASE, which should leave way more than
> enough room for errata ids. Since the code already checks if the
> patch_id is greater than the errata number, I can drop the
> "if (alt->patch_id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE)" check.

Ah, ye, I was being dumb - I was somehow thinking that you were using
the errata patch function to patch this, which obviously wouldn't be a
good design. If that had been the case, you'd never patch anything, but
you patch the extensions using the cpufeature patch function so it all
works out.

If anything, I guess there could be an assert here somewhere that
enforces ERRATA_VENDOR_NUMBER < VENDOR_EXT_BASE.

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  reply	other threads:[~2024-04-26 20:37 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-21  1:04 [PATCH v3 00/17] riscv: Support vendor extensions and xtheadvector Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 01/17] riscv: cpufeature: Fix thead vector hwcap removal Charlie Jenkins
2024-04-26  8:15   ` Guo Ren
2024-04-21  1:04 ` [PATCH v3 02/17] dt-bindings: riscv: Add xtheadvector ISA extension description Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 03/17] dt-bindings: riscv: cpus: add a vlen register length property Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 04/17] riscv: vector: Use vlenb from DT Charlie Jenkins
2024-04-26 15:17   ` Conor Dooley
2024-04-26 16:21     ` Conor Dooley
2024-04-26 17:03       ` Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 05/17] riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 06/17] riscv: Fix extension subset checking Charlie Jenkins
2024-04-24 14:22   ` Alexandre Ghiti
2024-04-24 14:51     ` Conor Dooley
2024-04-24 15:13       ` Charlie Jenkins
2024-04-24 15:21         ` Conor Dooley
2024-04-24 15:36           ` Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 07/17] riscv: Extend cpufeature.c to detect vendor extensions Charlie Jenkins
2024-04-26 16:00   ` Conor Dooley
2024-04-26 18:00     ` Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 08/17] riscv: Introduce vendor variants of extension helpers Charlie Jenkins
2024-04-26 16:19   ` Conor Dooley
2024-04-26 20:01     ` Charlie Jenkins
2024-04-26 20:37       ` Conor Dooley [this message]
2024-04-21  1:04 ` [PATCH v3 09/17] riscv: drivers: Convert xandespmu to use the vendor extension framework Charlie Jenkins
2024-04-26 16:25   ` Conor Dooley
2024-04-26 20:34     ` Charlie Jenkins
2024-04-26 20:46       ` Conor Dooley
2024-04-21  1:04 ` [PATCH v3 10/17] RISC-V: define the elements of the VCSR vector CSR Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 11/17] riscv: csr: Add CSR encodings for VCSR_VXRM/VCSR_VXSAT Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 12/17] riscv: Add xtheadvector instruction definitions Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 13/17] riscv: vector: Support xtheadvector save/restore Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 14/17] riscv: hwprobe: Add thead vendor extension probing Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 15/17] riscv: hwprobe: Document thead vendor extensions and xtheadvector extension Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 16/17] selftests: riscv: Fix vector tests Charlie Jenkins
2024-04-21  1:04 ` [PATCH v3 17/17] selftests: riscv: Support xtheadvector in " Charlie Jenkins

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