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From: Karsten Merker <merker@debian.org>
To: Anup Patel <anup@brainfault.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
	Palmer Dabbelt <palmer@sifive.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"zong@andestech.com" <zong@andestech.com>,
	Atish Patra <atish.patra@wdc.com>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>
Cc: Karsten Merker <merker@debian.org>
Subject: Re: [PATCH] RISC-V: Add an Image header that boot loader can parse.
Date: Wed, 1 May 2019 22:32:48 +0200	[thread overview]
Message-ID: <20190501203248.oadcldefusc2ighv@excalibur.cnev.de> (raw)
In-Reply-To: <20190501195443.trgjv6tujctsw5sw@excalibur.cnev.de>

On Wed, May 01, 2019 at 09:54:43PM +0200, Karsten Merker wrote:
> On Wed, May 01, 2019 at 10:41:52PM +0530, Anup Patel wrote:
> > On Wed, May 1, 2019 at 10:30 PM Mark Rutland <mark.rutland@arm.com> wrote:
> > > On Mon, Apr 29, 2019 at 10:42:40PM -0700, Atish Patra wrote:
> > > > On 4/29/19 4:40 PM, Palmer Dabbelt wrote:
> > > > > On Tue, 23 Apr 2019 16:25:06 PDT (-0700), atish.patra@wdc.com wrote:

> Probably I'm missing something obvious, but I cannot completely
> follow you here. My understanding is as follows:
[...]
> If the first byte in a PE/COFF header has to be an ASCII "M",
> that is 01001101 in binary.  RISC-V is little-endian and the last
> two bits of the lowest-value byte define the type of instruction. 
> According to the chapter "Base Instruction-Length Encoding" in
> the RISC-V ISA spec everything except 11 as the lowest bits
> denotes a compressed instruction and if I have puzzeled together
> the the various instruction bits correctly, ASCII "MZ" would be
> excuted as a compressed load immediate to x9/s1, wouldn't it?

Sorry, I have misinterpreted a bitfield in the spec, it's indeed
a compressed load immediate to x20/s4.

Regards,
Karsten
-- 
Ich widerspreche hiermit ausdrücklich der Nutzung sowie der
Weitergabe meiner personenbezogenen Daten für Zwecke der Werbung
sowie der Markt- oder Meinungsforschung.

WARNING: multiple messages have this Message-ID (diff)
From: Karsten Merker <merker@debian.org>
To: Anup Patel <anup@brainfault.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
	Palmer Dabbelt <palmer@sifive.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"zong@andestech.com" <zong@andestech.com>,
	Atish Patra <atish.patra@wdc.com>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>
Cc: Karsten Merker <merker@debian.org>
Subject: Re: [PATCH] RISC-V: Add an Image header that boot loader can parse.
Date: Wed, 1 May 2019 22:32:48 +0200	[thread overview]
Message-ID: <20190501203248.oadcldefusc2ighv@excalibur.cnev.de> (raw)
In-Reply-To: <20190501195443.trgjv6tujctsw5sw@excalibur.cnev.de>

On Wed, May 01, 2019 at 09:54:43PM +0200, Karsten Merker wrote:
> On Wed, May 01, 2019 at 10:41:52PM +0530, Anup Patel wrote:
> > On Wed, May 1, 2019 at 10:30 PM Mark Rutland <mark.rutland@arm.com> wrote:
> > > On Mon, Apr 29, 2019 at 10:42:40PM -0700, Atish Patra wrote:
> > > > On 4/29/19 4:40 PM, Palmer Dabbelt wrote:
> > > > > On Tue, 23 Apr 2019 16:25:06 PDT (-0700), atish.patra@wdc.com wrote:

> Probably I'm missing something obvious, but I cannot completely
> follow you here. My understanding is as follows:
[...]
> If the first byte in a PE/COFF header has to be an ASCII "M",
> that is 01001101 in binary.  RISC-V is little-endian and the last
> two bits of the lowest-value byte define the type of instruction. 
> According to the chapter "Base Instruction-Length Encoding" in
> the RISC-V ISA spec everything except 11 as the lowest bits
> denotes a compressed instruction and if I have puzzeled together
> the the various instruction bits correctly, ASCII "MZ" would be
> excuted as a compressed load immediate to x9/s1, wouldn't it?

Sorry, I have misinterpreted a bitfield in the spec, it's indeed
a compressed load immediate to x20/s4.

Regards,
Karsten
-- 
Ich widerspreche hiermit ausdrücklich der Nutzung sowie der
Weitergabe meiner personenbezogenen Daten für Zwecke der Werbung
sowie der Markt- oder Meinungsforschung.

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2019-05-01 20:33 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 23:25 [PATCH] RISC-V: Add an Image header that boot loader can parse Atish Patra
2019-04-23 23:25 ` Atish Patra
2019-04-29 23:40 ` Palmer Dabbelt
2019-04-29 23:40   ` Palmer Dabbelt
2019-04-30  5:42   ` Atish Patra
2019-04-30  5:42     ` Atish Patra
2019-05-01 16:43     ` Karsten Merker
2019-05-01 16:43       ` Karsten Merker
2019-05-01 17:02       ` Anup Patel
2019-05-01 17:02         ` Anup Patel
2019-05-01 17:32         ` Atish Patra
2019-05-01 17:32           ` Atish Patra
2019-05-01 17:00     ` Mark Rutland
2019-05-01 17:00       ` Mark Rutland
2019-05-01 17:11       ` Anup Patel
2019-05-01 17:11         ` Anup Patel
2019-05-01 17:35         ` Mark Rutland
2019-05-01 17:35           ` Mark Rutland
2019-05-01 19:54         ` Karsten Merker
2019-05-01 19:54           ` Karsten Merker
2019-05-01 20:32           ` Karsten Merker [this message]
2019-05-01 20:32             ` Karsten Merker

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