From: Christoph Hellwig <hch@infradead.org>
To: Anup Patel <Anup.Patel@wdc.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
Palmer Dabbelt <palmer@sifive.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Atish Patra <Atish.Patra@wdc.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>
Subject: Re: [PATCH v2 1/3] RISC-V: Add separate asm/encoding.h for spec related defines
Date: Sun, 14 Apr 2019 22:49:49 -0700 [thread overview]
Message-ID: <20190415054949.GA9279@infradead.org> (raw)
In-Reply-To: <20190413153807.116227-2-anup.patel@wdc.com>
On Sat, Apr 13, 2019 at 03:38:35PM +0000, Anup Patel wrote:
> It's better to have all RISC-V spec related defines in one place
> so this patch adds separate asm/encoding.h for such defines which
> can be included in assembly as well as C code.
As per the discussion of version 1 on Saturday I disagree with this
move. There is both a philosophical and a practical reason for that:
a) in RISC-V CSR access is really nicely split out into a separate
number space, just accessed through a few special instructions.
It has no overlap with the rest of instruction encoding
b) <asm/csr.h> is pulled into just about every file build in the kernel
though <asm/irqflags.h>, <asm/switch_to.h> and <asm/thread_info.h>
So even if you want to later add a new <asm/encoding.h> for instruction
encoding details later, I'd rather prefer to keep CSR access separate
from it.
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next prev parent reply other threads:[~2019-04-15 5:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-13 15:38 [PATCH v2 0/3] Allow accessing CSR using CSR number Anup Patel
2019-04-13 15:38 ` [PATCH v2 1/3] RISC-V: Add separate asm/encoding.h for spec related defines Anup Patel
2019-04-15 5:49 ` Christoph Hellwig [this message]
2019-04-15 7:29 ` Anup Patel
2019-04-13 15:38 ` [PATCH v2 2/3] RISC-V: Add interrupt related SCAUSE defines in asm/encoding.h Anup Patel
2019-04-13 15:38 ` [PATCH v2 3/3] RISC-V: Access CSRs using CSR numbers Anup Patel
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