From: Alan Stern <stern@rowland.harvard.edu>
To: Alexander Holler <holler@ahsoftware.de>
Cc: gregkh@suse.de, Rabin Vincent <rabin@rab.in>,
<linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute
Date: Thu, 16 Jun 2011 13:09:58 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1106161308310.2204-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <1308241030-15201-1-git-send-email-holler@ahsoftware.de>
On Thu, 16 Jun 2011, Alexander Holler wrote:
> In commit 139540170d9d9b7ead3caaf540f161756b356d56 the attribute
> packed is removed from the structs which are used to access the EHCI-registers.
>
> This is done to circumvent a problem with gcc 4.6, which might access members of
> packed structs on a byte by byte basis. But using packed, aligned(4) fixes that
> too and is imho the better solution. Otherwise (without packed) the compiler would be free
> to choose whatever alignment he thinks fits best, which might be e.g. 8-byte on 64-bit machines.
Is that really true? I thought the compiler was not allowed to insert
padding if the natural alignment of the data types didn't require any.
Alan Stern
WARNING: multiple messages have this Message-ID (diff)
From: stern@rowland.harvard.edu (Alan Stern)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute
Date: Thu, 16 Jun 2011 13:09:58 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1106161308310.2204-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <1308241030-15201-1-git-send-email-holler@ahsoftware.de>
On Thu, 16 Jun 2011, Alexander Holler wrote:
> In commit 139540170d9d9b7ead3caaf540f161756b356d56 the attribute
> packed is removed from the structs which are used to access the EHCI-registers.
>
> This is done to circumvent a problem with gcc 4.6, which might access members of
> packed structs on a byte by byte basis. But using packed, aligned(4) fixes that
> too and is imho the better solution. Otherwise (without packed) the compiler would be free
> to choose whatever alignment he thinks fits best, which might be e.g. 8-byte on 64-bit machines.
Is that really true? I thought the compiler was not allowed to insert
padding if the natural alignment of the data types didn't require any.
Alan Stern
next prev parent reply other threads:[~2011-06-16 17:10 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-27 14:34 [PATCH] echi: remove structure packing from ehci_def Rabin Vincent
2011-04-27 14:34 ` Rabin Vincent
2011-04-27 15:15 ` Sergei Shtylyov
2011-04-27 15:15 ` Sergei Shtylyov
2011-04-27 15:37 ` [PATCHv2] " Rabin Vincent
2011-04-27 15:37 ` Rabin Vincent
2011-06-16 16:17 ` [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute Alexander Holler
2011-06-16 16:17 ` [PATCH] USB: ehci: use packed, aligned(4) " Alexander Holler
2011-06-16 17:09 ` Alan Stern [this message]
2011-06-16 17:09 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-16 17:55 ` Arnd Bergmann
2011-06-16 17:55 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-16 19:25 ` [PATCH] USB: ehci: use packed,aligned(4) " Alexander Holler
2011-06-16 19:25 ` Alexander Holler
2011-06-16 19:46 ` Alan Stern
2011-06-16 19:46 ` Alan Stern
2011-06-16 20:10 ` Alexander Holler
2011-06-16 20:10 ` Alexander Holler
2011-06-16 20:20 ` Arnd Bergmann
2011-06-16 20:20 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-19 15:02 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-19 15:02 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-19 19:00 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-19 19:00 ` Alan Stern
2011-06-19 20:02 ` Arnd Bergmann
2011-06-19 20:02 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-19 20:11 ` [PATCH] USB: ehci: use packed,aligned(4) " Arnd Bergmann
2011-06-19 20:11 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-19 21:39 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-19 21:39 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-19 21:27 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-19 21:27 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 15:03 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 15:03 ` Alan Stern
2011-06-20 16:16 ` Nicolas Pitre
2011-06-20 16:16 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 16:48 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 16:48 ` Alan Stern
2011-06-20 16:58 ` Arnd Bergmann
2011-06-20 16:58 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-20 19:02 ` Russell King - ARM Linux
2011-06-20 19:02 ` Russell King - ARM Linux
2011-06-20 19:20 ` Nicolas Pitre
2011-06-20 19:20 ` Nicolas Pitre
2011-06-20 19:29 ` Nicolas Pitre
2011-06-20 19:29 ` Nicolas Pitre
2011-06-20 17:10 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-20 17:10 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 17:35 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 17:35 ` Alan Stern
2011-06-20 18:48 ` Russell King - ARM Linux
2011-06-20 18:48 ` Russell King - ARM Linux
2011-06-20 20:26 ` Arnd Bergmann
2011-06-20 20:26 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-20 20:50 ` Nicolas Pitre
2011-06-20 20:50 ` Nicolas Pitre
2011-06-20 20:55 ` [PATCH] USB: ehci: use packed,aligned(4) " Russell King - ARM Linux
2011-06-20 20:55 ` Russell King - ARM Linux
2011-06-20 21:23 ` Arnd Bergmann
2011-06-20 21:23 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-20 22:23 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-20 22:23 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-21 11:25 ` [PATCH] USB: ehci: use packed,aligned(4) " Arnd Bergmann
2011-06-21 11:25 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-25 1:25 ` Nicolas Pitre
2011-06-25 8:09 ` Arnd Bergmann
2011-06-28 18:51 ` Nicolas Pitre
2011-06-29 10:56 ` Arnd Bergmann
2011-06-20 19:14 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-20 19:14 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 19:32 ` Russell King - ARM Linux
2011-06-20 19:32 ` Russell King - ARM Linux
2011-06-20 20:14 ` Arnd Bergmann
2011-06-20 20:14 ` Arnd Bergmann
2011-06-20 20:42 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 20:42 ` Alan Stern
2011-06-20 22:36 ` Nicolas Pitre
2011-06-20 22:36 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-21 15:06 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-21 15:06 ` Alan Stern
2011-06-20 17:39 ` Alexander Holler
2011-06-20 17:39 ` Alexander Holler
2011-06-20 18:39 ` Alan Stern
2011-06-20 18:39 ` Alan Stern
2011-06-20 18:46 ` Alexander Holler
2011-06-20 18:46 ` Alexander Holler
2011-06-20 18:57 ` Alan Stern
2011-06-20 18:57 ` Alan Stern
2011-06-20 19:56 ` Nicolas Pitre
2011-06-20 19:56 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 21:04 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 21:04 ` Alan Stern
2011-06-20 22:31 ` Nicolas Pitre
2011-06-20 22:31 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-21 14:58 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-21 14:58 ` Alan Stern
2011-06-21 20:41 ` Nicolas Pitre
2011-06-21 20:41 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-22 6:23 ` [PATCH] USB: ehci: use packed,aligned(4) " Alexander Holler
2011-06-22 6:23 ` Alexander Holler
2011-06-20 20:09 ` Arnd Bergmann
2011-06-20 20:09 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-20 21:05 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-20 21:05 ` Alan Stern
2011-06-20 20:07 ` Arnd Bergmann
2011-06-20 20:07 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-20 20:28 ` [PATCH] USB: ehci: use packed,aligned(4) " Nicolas Pitre
2011-06-20 20:28 ` [PATCH] USB: ehci: use packed, aligned(4) " Nicolas Pitre
2011-06-20 20:39 ` Arnd Bergmann
2011-06-20 20:39 ` Arnd Bergmann
2011-06-20 21:03 ` Nicolas Pitre
2011-06-20 21:03 ` Nicolas Pitre
2011-06-23 9:47 ` Alexander Holler
2011-06-23 9:47 ` Alexander Holler
2011-06-23 14:25 ` Alan Stern
2011-06-23 14:25 ` Alan Stern
2011-06-24 11:40 ` Alexander Holler
2011-06-24 11:40 ` Alexander Holler
2011-06-20 16:26 ` [PATCH] USB: ehci: use packed,aligned(4) " Arnd Bergmann
2011-06-20 16:26 ` [PATCH] USB: ehci: use packed, aligned(4) " Arnd Bergmann
2011-06-16 20:30 ` [PATCH] USB: ehci: use packed,aligned(4) " Alan Stern
2011-06-16 20:30 ` Alan Stern
2011-06-16 18:16 ` Alexander Holler
2011-06-16 18:16 ` Alexander Holler
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