From: Guo Ren <guoren@kernel.org>
To: Conor Dooley <conor@kernel.org>
Cc: Jisheng Zhang <jszhang@kernel.org>,
palmer@dabbelt.com, heiko@sntech.de, charlie@rivosinc.com,
Palmer Dabbelt <palmer@rivosinc.com>,
Conor Dooley <conor.dooley@microchip.com>,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2] RISC-V: Don't trust V from the riscv,isa DT property on T-Head CPUs
Date: Fri, 14 Jul 2023 14:14:45 +0800 [thread overview]
Message-ID: <CAJF2gTRy5eK73=d6s7CVy9m9pB8p4rAoMHM3cZFwzg=AuF7TDA@mail.gmail.com> (raw)
In-Reply-To: <20230713-statutory-balance-f2c9e862f2e3@spud>
On Fri, Jul 14, 2023 at 1:45 AM Conor Dooley <conor@kernel.org> wrote:
>
> On Thu, Jul 13, 2023 at 01:33:56PM -0400, Guo Ren wrote:
> > On Thu, Jul 13, 2023 at 12:48 PM Jisheng Zhang <jszhang@kernel.org> wrote:
> > > On Wed, Jul 12, 2023 at 06:48:02PM +0100, Conor Dooley wrote:
>
> > > > + /*
> > > > + * "V" in ISA strings is ambiguous in practice: it should mean
> > > > + * just the standard V-1.0 but vendors aren't well behaved.
> > > > + * Many vendors with T-Head CPU cores which implement the 0.7.1
> > > > + * version of the vector specification put "v" into their DTs
> > > > + * and no T-Head CPU cores with the standard version of vector
> > > > + * are in circulation yet.
>
> > T-HEAD's vector 1.0 SoCs is in circulation. Kendryte K230 is the
> > shipped SoC chip, which vendor id = THEAD_VENDOR_ID and with vector
> > 1.0.
>
> Where can I buy one, if it is in circulation?
> Googling in English might not be the best thing to do, but doing so I
> could find basically no information on the k230 - I did know it existed
> and tried to find some info on it before sending the patch.
> If it is not in circulation, then the comment is not inaccurate & when
> they do arrive they can use the new dedicated property to convey support
> for vector.
>
> > > > + * Platforms with T-Head CPU cores that support the standard
> > > > + * version of vector must provide the explicit V property,
> > > > + * which is well defined.
> > > > + */
> > > > + if (acpi_disabled && riscv_cached_mvendorid(cpu) == THEAD_VENDOR_ID) {
> > If you insist on doing this, please:
> >
> > if (acpi_disabled && riscv_cached_mvendorid(cpu) == THEAD_VENDOR_ID &&
> > riscv_cached_marchid(cpu) == 0 && riscv_cached_mimpid(cpu) == 0) {
>
> Why? Does the c908 report non-zero mimpid/marchid?
Yes
> If yes, does it need either the errata for CMOs or the page tables?
C908 is compatible to RVA22 Profile, here is the detail link:
https://xrvm.com/cpu-details?id=4107904466789928960
>
> Thanks,
> Conor.
--
Best Regards
Guo Ren
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next prev parent reply other threads:[~2023-07-14 6:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 17:48 [PATCH v2] RISC-V: Don't trust V from the riscv,isa DT property on T-Head CPUs Conor Dooley
2023-07-13 16:36 ` Jisheng Zhang
2023-07-13 16:56 ` Palmer Dabbelt
2023-07-13 17:04 ` Conor Dooley
2023-07-13 17:12 ` Jisheng Zhang
2023-07-13 17:36 ` Conor Dooley
2023-07-13 18:20 ` Conor Dooley
2023-07-13 17:33 ` Guo Ren
2023-07-13 17:43 ` Palmer Dabbelt
2023-07-14 6:07 ` Guo Ren
2023-07-13 17:45 ` Conor Dooley
2023-07-14 6:14 ` Guo Ren [this message]
2023-07-14 11:10 ` Conor Dooley
2023-07-14 18:45 ` Conor Dooley
2023-07-15 6:11 ` Guo Ren
2023-07-15 6:07 ` Guo Ren
2023-07-13 18:47 ` Rémi Denis-Courmont
2023-07-13 18:50 ` Rémi Denis-Courmont
2023-07-14 19:21 ` Conor Dooley
2023-07-15 6:12 ` Guo Ren
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