From: James Hogan <james.hogan@imgtec.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [RFC PATCH v1 00/40] Meta Linux Kernel Port
Date: Tue, 13 Nov 2012 09:43:59 +0000 [thread overview]
Message-ID: <50A2165F.4010202@imgtec.com> (raw)
In-Reply-To: <201211121910.09395.arnd@arndb.de>
On 12/11/12 19:10, Arnd Bergmann wrote:
> On Monday 12 November 2012, James Hogan wrote:
>> Note that Meta doesn't support unaligned accesses anyway so use of
>> __packed on MMIO is likely broken from the outset.
>
> The problem is actually the opposite: Some people incorrectly annotate
> structures that are always aligned to be __packed. This has no effect
> on architectures that support unaligned accesses, but causes the
> access to be split into byte sized loads and stores on architectures
> like Meta that cannot.
>
> Note also that gcc is free to split any accesses for whatever reason
> it deems necessary.
Hmm, I found the thread "ARM unaligned MMIO access with
attribute((packed))" which appears to be one of the problems you're
referring to. With some experimentation I can't reproduce this kind of
problem with our current compiler, but it's certainly cause for concern.
Thanks
James
next prev parent reply other threads:[~2012-11-13 9:44 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 16:13 [RFC PATCH v1 00/40] Meta Linux Kernel Port James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 01/40] asm-generic/io.h: remove asm/cacheflush.h include James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 02/40] asm-generic/unistd.h: handle symbol prefixes in cond_syscall James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 03/40] Add CONFIG_HAVE_64BIT_ALIGNED_STRUCT for taskstats James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 04/40] trace/ring_buffer: handle 64bit aligned structs James Hogan
2012-10-31 17:59 ` Steven Rostedt
2012-10-31 18:19 ` James Hogan
2012-11-01 17:32 ` Will Newton
2012-11-01 19:30 ` Steven Rostedt
2012-10-31 16:13 ` [RFC PATCH v1 05/40] Revert some of "binfmt_elf: cleanups" James Hogan
2012-10-31 16:13 ` James Hogan
2012-11-01 13:25 ` Mikael Pettersson
2012-11-01 13:25 ` Mikael Pettersson
2012-11-01 13:52 ` James Hogan
2012-11-01 13:52 ` James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 06/40] of/vendor-prefixes: add Imagination Technologies James Hogan
2012-11-01 1:38 ` Rob Herring
2012-11-01 9:20 ` James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 07/40] metag: Add MAINTAINERS entry James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 08/40] metag: Boot James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 11/40] metag: Signal handling James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 12/40] metag: Build infrastructure James Hogan
2012-10-31 19:35 ` Sam Ravnborg
2012-10-31 21:34 ` James Hogan
2012-11-02 9:40 ` James Hogan
2012-11-02 17:01 ` Sam Ravnborg
2012-11-09 14:46 ` Arnd Bergmann
2012-11-09 14:55 ` James Hogan
2012-11-20 15:06 ` James Hogan
2012-11-20 15:43 ` Arnd Bergmann
2012-11-20 16:01 ` James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 13/40] metag: Device tree James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 14/40] metag: Ptrace James Hogan
2012-11-08 7:17 ` Jonas Bonn
2012-11-09 9:26 ` James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 15/40] metag: Time keeping James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 16/40] metag: Traps James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 17/40] metag: IRQ handling James Hogan
2012-11-09 14:12 ` Arnd Bergmann
2012-11-20 16:08 ` James Hogan
2012-11-20 16:15 ` Arnd Bergmann
2012-12-18 13:25 ` James Hogan
2012-12-19 15:58 ` Arnd Bergmann
2012-12-20 10:14 ` James Hogan
2012-10-31 16:13 ` [RFC PATCH v1 18/40] metag: System Calls James Hogan
2012-11-09 14:20 ` Arnd Bergmann
2012-11-22 12:01 ` James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 19/40] metag: Scheduling/Process management James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 20/40] metag: Module support James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 21/40] metag: Atomics, locks and bitops James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 22/40] metag: Basic documentation James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 23/40] metag: SMP support James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 24/40] metag: DMA James Hogan
2012-11-09 14:25 ` Arnd Bergmann
2012-11-23 15:53 ` James Hogan
2012-11-23 16:20 ` James Hogan
2012-11-23 16:20 ` James Hogan
2012-11-23 16:47 ` Arnd Bergmann
2013-01-09 16:04 ` James Hogan
2013-01-09 16:04 ` James Hogan
2013-01-09 16:08 ` Arnd Bergmann
2012-11-23 16:47 ` Arnd Bergmann
2012-10-31 16:14 ` [RFC PATCH v1 25/40] metag: optimised library functions James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 26/40] metag: Stack unwinding James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 27/40] metag: various other headers James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 28/40] metag: Perf James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 29/40] metag: ftrace support James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 30/40] scripts/checkstack.pl: Add metag support James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 31/40] char: don't build rtc or genrtc on METAG James Hogan
2012-11-01 15:39 ` Greg KH
2012-11-01 17:33 ` James Hogan
2012-11-09 14:38 ` Arnd Bergmann
2012-10-31 16:14 ` [RFC PATCH v1 32/40] i8042: don't build " James Hogan
2012-11-09 14:28 ` Arnd Bergmann
2012-11-16 11:06 ` James Hogan
2012-11-16 15:20 ` Arnd Bergmann
2012-11-16 16:19 ` Geert Uytterhoeven
2012-11-16 16:43 ` Arnd Bergmann
2012-11-16 16:50 ` James Hogan
2012-11-16 17:20 ` Arnd Bergmann
2012-10-31 16:14 ` [RFC PATCH v1 33/40] parport: " James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 34/40] musb: don't redefine {read,write}s{l,w,b} on metag James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 35/40] vga console: don't build on METAG James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 36/40] metag: OProfile James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 37/40] metag: Various sysfs drivers James Hogan
2012-10-31 19:30 ` Greg KH
2012-10-31 19:41 ` James Hogan
2012-11-09 14:32 ` Arnd Bergmann
2012-11-09 14:35 ` James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 38/40] metag: add JTAG Debug Adapter (DA) support James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 39/40] tty/metag_da: add metag DA TTY driver James Hogan
2012-10-31 16:14 ` [RFC PATCH v1 40/40] fs: dafs: Add DAFS filesystem for metag James Hogan
2012-10-31 16:14 ` James Hogan
2012-10-31 16:42 ` Al Viro
2012-10-31 19:39 ` James Hogan
2012-10-31 19:39 ` James Hogan
2012-10-31 19:55 ` Myklebust, Trond
2012-10-31 21:39 ` James Hogan
2012-11-02 9:33 ` James Hogan
2012-10-31 16:26 ` [RFC PATCH v1 00/40] Meta Linux Kernel Port James Hogan
2012-11-09 15:06 ` Arnd Bergmann
2012-11-09 15:21 ` James Hogan
2012-11-09 15:58 ` Arnd Bergmann
2012-11-09 16:20 ` James Hogan
2012-11-09 21:55 ` Arnd Bergmann
2012-11-09 23:28 ` James Hogan
2012-11-12 16:59 ` James Hogan
2012-11-12 19:10 ` Arnd Bergmann
2012-11-13 9:43 ` James Hogan [this message]
2012-11-13 9:55 ` Arnd Bergmann
2012-10-31 22:33 ` Tony Breeds
2012-11-01 11:42 ` James Hogan
2012-11-01 23:28 ` Tony Breeds
2012-11-09 16:52 ` James Hogan
2012-11-09 15:16 ` Arnd Bergmann
2012-11-09 16:06 ` James Hogan
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