From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Kim Phillips <kim.phillips@freescale.com>
Cc: "Woodhouse, David" <david.woodhouse@intel.com>,
Borislav Petkov <bp@alien8.de>,
Andrew Morton <akpm@linux-foundation.org>,
Daniel Santos <daniel.santos@pobox.com>,
David Rientjes <rientjes@google.com>,
Rusty Russell <rusty@rustcorp.com.au>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Rob Herring <robherring2@gmail.com>
Subject: Re: [RFC] arm: use built-in byte swap function
Date: Thu, 7 Feb 2013 18:13:15 +0000 [thread overview]
Message-ID: <20130207181315.GM17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20130206191905.ac8eb6743e69425f30888704@freescale.com>
On Wed, Feb 06, 2013 at 07:19:05PM -0600, Kim Phillips wrote:
> either that, or link with libgcc - why does arch/arm64 do this and
> arch/arm not? It's not obvious from git log.
We want to be in control of what code the kernel runs, and that means
not using libgcc. libgcc can do all sorts of stuff because it makes
assumptions about the environment which it is executing in (glibc).
For example, it assumes there may be a GOT, and that it can issue SWI
calls...
However, the biggest reason not to use libgcc is that we want to control
what gets used in the kernel - for example, no floating point, and no
use of 64 x 64bit division.
So all round, using libgcc in AArch32 would bring us a number of issues
that we don't get with the current approach.
AArch64 uses it because it's maintained entirely separately and the
decision has been made by other people - and some of these concerns do
not exist on a 64-bit architecture.
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] arm: use built-in byte swap function
Date: Thu, 7 Feb 2013 18:13:15 +0000 [thread overview]
Message-ID: <20130207181315.GM17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20130206191905.ac8eb6743e69425f30888704@freescale.com>
On Wed, Feb 06, 2013 at 07:19:05PM -0600, Kim Phillips wrote:
> either that, or link with libgcc - why does arch/arm64 do this and
> arch/arm not? It's not obvious from git log.
We want to be in control of what code the kernel runs, and that means
not using libgcc. libgcc can do all sorts of stuff because it makes
assumptions about the environment which it is executing in (glibc).
For example, it assumes there may be a GOT, and that it can issue SWI
calls...
However, the biggest reason not to use libgcc is that we want to control
what gets used in the kernel - for example, no floating point, and no
use of 64 x 64bit division.
So all round, using libgcc in AArch32 would bring us a number of issues
that we don't get with the current approach.
AArch64 uses it because it's maintained entirely separately and the
decision has been made by other people - and some of these concerns do
not exist on a 64-bit architecture.
next prev parent reply other threads:[~2013-02-07 18:19 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-29 1:30 [RFC] arm: use built-in byte swap function Kim Phillips
2013-01-29 1:30 ` Kim Phillips
2013-01-29 8:35 ` Borislav Petkov
2013-01-29 8:35 ` Borislav Petkov
2013-01-29 16:46 ` Woodhouse, David
2013-01-29 16:46 ` Woodhouse, David
2013-01-29 17:42 ` Borislav Petkov
2013-01-29 17:42 ` Borislav Petkov
2013-01-29 17:55 ` Woodhouse, David
2013-01-29 17:55 ` Woodhouse, David
2013-01-29 18:10 ` Borislav Petkov
2013-01-29 18:10 ` Borislav Petkov
2013-01-30 10:22 ` Woodhouse, David
2013-01-30 10:22 ` Woodhouse, David
2013-01-31 2:09 ` Kim Phillips
2013-01-31 2:09 ` Kim Phillips
2013-01-31 6:44 ` Borislav Petkov
2013-01-31 6:44 ` Borislav Petkov
2013-01-31 9:28 ` Russell King - ARM Linux
2013-01-31 9:28 ` Russell King - ARM Linux
2013-01-31 20:59 ` Kim Phillips
2013-01-31 20:59 ` Kim Phillips
2013-01-31 21:33 ` Borislav Petkov
2013-01-31 21:33 ` Borislav Petkov
2013-01-31 22:11 ` Woodhouse, David
2013-01-31 22:11 ` Woodhouse, David
2013-02-01 0:37 ` [PATCH v4] " Kim Phillips
2013-02-01 0:37 ` Kim Phillips
2013-02-01 10:46 ` Russell King - ARM Linux
2013-02-01 10:46 ` Russell King - ARM Linux
2013-02-01 1:17 ` [RFC] " Russell King - ARM Linux
2013-02-01 1:17 ` Russell King - ARM Linux
2013-02-01 7:33 ` Woodhouse, David
2013-02-01 7:33 ` Woodhouse, David
2013-02-06 3:04 ` Kim Phillips
2013-02-06 3:04 ` Kim Phillips
2013-02-06 9:02 ` Woodhouse, David
2013-02-06 9:02 ` Woodhouse, David
2013-02-07 1:19 ` Kim Phillips
2013-02-07 1:19 ` Kim Phillips
2013-02-07 10:19 ` Will Newton
2013-02-07 10:19 ` Will Newton
2013-02-07 10:43 ` Catalin Marinas
2013-02-07 10:43 ` Catalin Marinas
2013-02-07 18:13 ` Russell King - ARM Linux [this message]
2013-02-07 18:13 ` Russell King - ARM Linux
2013-02-08 17:25 ` Woodhouse, David
2013-02-08 17:25 ` Woodhouse, David
2013-02-08 20:04 ` Nicolas Pitre
2013-02-08 20:04 ` Nicolas Pitre
2013-02-08 22:40 ` Woodhouse, David
2013-02-08 22:40 ` Woodhouse, David
2013-02-08 22:47 ` Nicolas Pitre
2013-02-08 22:47 ` Nicolas Pitre
2013-02-09 1:12 ` Kim Phillips
2013-02-09 1:12 ` Kim Phillips
2013-02-09 3:16 ` Nicolas Pitre
2013-02-09 3:16 ` Nicolas Pitre
2013-02-20 2:31 ` Kim Phillips
2013-02-20 2:31 ` Kim Phillips
2013-02-20 2:38 ` Stephen Boyd
2013-02-20 2:38 ` Stephen Boyd
2013-02-20 3:17 ` Nicolas Pitre
2013-02-20 3:17 ` Nicolas Pitre
2013-02-20 10:38 ` Woodhouse, David
2013-02-20 10:38 ` Woodhouse, David
2013-02-20 13:36 ` Nicolas Pitre
2013-02-20 13:36 ` Nicolas Pitre
2013-02-20 13:44 ` Woodhouse, David
2013-02-20 13:44 ` Woodhouse, David
2013-02-20 14:06 ` Nicolas Pitre
2013-02-20 14:06 ` Nicolas Pitre
2013-02-20 14:53 ` Woodhouse, David
2013-02-20 14:53 ` Woodhouse, David
2013-02-20 15:43 ` Nicolas Pitre
2013-02-20 15:43 ` Nicolas Pitre
2013-02-21 3:49 ` Kim Phillips
2013-02-21 3:49 ` Kim Phillips
2013-02-21 4:29 ` Nicolas Pitre
2013-02-21 4:29 ` Nicolas Pitre
2013-02-21 6:52 ` Kim Phillips
2013-02-21 6:52 ` Kim Phillips
2013-02-21 16:40 ` Nicolas Pitre
2013-02-21 16:40 ` Nicolas Pitre
2013-02-22 2:33 ` Kim Phillips
2013-02-22 2:33 ` Kim Phillips
2013-02-22 3:40 ` Nicolas Pitre
2013-02-22 3:40 ` Nicolas Pitre
2013-02-23 1:40 ` [PATCH v6] " Kim Phillips
2013-02-23 1:40 ` Kim Phillips
2013-02-23 2:40 ` Nicolas Pitre
2013-02-23 2:40 ` Nicolas Pitre
2013-02-23 23:20 ` Woodhouse, David
2013-02-23 23:20 ` Woodhouse, David
2013-05-23 16:46 ` [PATCH v7] " Kim Phillips
2013-05-23 16:46 ` Kim Phillips
2013-05-23 20:09 ` Nicolas Pitre
2013-05-23 20:09 ` Nicolas Pitre
2013-05-23 23:13 ` Russell King - ARM Linux
2013-05-23 23:13 ` Russell King - ARM Linux
2013-06-06 22:12 ` Russell King - ARM Linux
2013-06-06 22:12 ` Russell King - ARM Linux
2013-06-06 22:23 ` Borislav Petkov
2013-06-06 22:23 ` Borislav Petkov
2013-06-07 0:03 ` Stephen Rothwell
2013-06-07 0:03 ` Stephen Rothwell
2013-05-26 5:38 ` Dirk Behme
2013-05-26 9:30 ` Woodhouse, David
2013-10-27 2:41 ` Nicolas Pitre
2013-10-27 2:41 ` Nicolas Pitre
2013-11-05 21:45 ` Kim Phillips
2013-11-05 21:45 ` Kim Phillips
2013-02-21 16:37 ` [RFC] " Woodhouse, David
2013-02-21 16:37 ` Woodhouse, David
2013-02-21 17:27 ` Nicolas Pitre
2013-02-21 17:27 ` Nicolas Pitre
2013-03-13 13:35 ` Woodhouse, David
2013-03-13 13:35 ` Woodhouse, David
2013-01-29 14:13 ` Russell King - ARM Linux
2013-01-29 14:13 ` Russell King - ARM Linux
2013-01-29 14:43 ` Woodhouse, David
2013-01-29 14:43 ` Woodhouse, David
2013-01-29 14:53 ` Rob Herring
2013-01-29 14:53 ` Rob Herring
2013-01-29 15:10 ` Woodhouse, David
2013-01-29 15:10 ` Woodhouse, David
2013-01-31 11:44 Woodhouse, David
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