From: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Alistair Francis <alistair.francis@wdc.com>,
Bin Meng <bmeng.cn@gmail.com>, Weiwei Li <liwei1518@gmail.com>,
Daniel Henrique Barboza <dbarboza@ventanamicro.com>,
Liu Zhiwei <zhiwei_liu@linux.alibaba.com>,
qemu-riscv@nongnu.org, qemu-devel@nongnu.org,
Anup Patel <anup@brainfault.org>,
Atish Patra <atishp@atishpatra.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] target/riscv: enable floating point unit
Date: Wed, 18 Sep 2024 17:49:26 +0200 [thread overview]
Message-ID: <620daf0d-caf8-4fe5-901e-2abadb751392@canonical.com> (raw)
In-Reply-To: <20240918-4e2df3f0cabdb8002d7315d9@orel>
On 18.09.24 15:56, Andrew Jones wrote:
> Thanks Heinrich, I had also forgotten that distinction. So the last
> question is whether or not we want to reset mstatus.FS to 1 instead of 3,
> as is done in this patch.
>
> Thanks,
> drew
If the FD flag set to 3 (Dirty) indicates that "the corresponding state
has potentially been modified since the last context save". Upon context
switches the value of the floating point registers has to be saved.
The value 1 (Initial) implies that saving the registers on a context
change is not needed.
3 (Dirty) is the safest choice. This is why OpenSBI is also using it.
For reference:
3.1.6.6. Extension Context Status in mstatus Register
The RISC-V Instruction Set Manual: Volume II - Privileged Architecture
Version 2024-04-11
Best regards
Heinrich
next prev parent reply other threads:[~2024-09-18 15:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240916181633.366449-1-heinrich.schuchardt@canonical.com>
[not found] ` <20240917-f45624310204491aede04703@orel>
[not found] ` <15c359a4-b3c1-4cb0-be2e-d5ca5537bc5b@canonical.com>
[not found] ` <20240917-b13c51d41030029c70aab785@orel>
2024-09-17 16:45 ` Heinrich Schuchardt
2024-09-18 6:05 ` Andrew Jones
2024-09-18 11:10 ` Peter Maydell
2024-09-18 13:06 ` Heinrich Schuchardt
2024-09-18 13:12 ` Peter Maydell
2024-09-18 13:49 ` Heinrich Schuchardt
2024-09-18 13:56 ` Andrew Jones
2024-09-18 15:49 ` Heinrich Schuchardt [this message]
2024-09-18 15:32 ` Peter Maydell
2024-09-18 16:27 ` Heinrich Schuchardt
2024-10-08 0:45 ` Alistair Francis
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=620daf0d-caf8-4fe5-901e-2abadb751392@canonical.com \
--to=heinrich.schuchardt@canonical.com \
--cc=ajones@ventanamicro.com \
--cc=alistair.francis@wdc.com \
--cc=anup@brainfault.org \
--cc=aou@eecs.berkeley.edu \
--cc=atishp@atishpatra.org \
--cc=bmeng.cn@gmail.com \
--cc=dbarboza@ventanamicro.com \
--cc=kvm-riscv@lists.infradead.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=liwei1518@gmail.com \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
--cc=qemu-riscv@nongnu.org \
--cc=zhiwei_liu@linux.alibaba.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®