From: Olof Johansson <olof@lixom.net>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v2 02/31] arm64: Kernel booting and initialisation
Date: Wed, 15 Aug 2012 10:06:13 -0700 [thread overview]
Message-ID: <20120815170613.GA2892@quad.lixom.net> (raw)
In-Reply-To: <201208151320.02313.arnd@arndb.de>
On Wed, Aug 15, 2012 at 01:20:02PM +0000, Arnd Bergmann wrote:
> On Tuesday 14 August 2012, Catalin Marinas wrote:
>
> > +The AArch64 exception model is made up of a number of exception levels
> > +(EL0 - EL3), with EL0 and EL1 having a secure and a non-secure
> > +counterpart. EL2 is the hypervisor level and exists only in non-secure
> > +mode. EL3 is the highest priority level and exists only in secure mode.
>
> I'm always confused by a description like this. It sounds like you cannot
> have a hypervisor if you have code running in secure mode in EL3. What
> I instead understand is that you enter non-secure mode by going from
> EL3 into EL2.
>
> > +2. Setup the device tree
> > +-------------------------
> > +
> > +Requirement: MANDATORY
> > +
> > +The device tree blob (dtb) must be no bigger than 2 megabytes in size
> > +and placed at a 2-megabyte boundary within the first 512 megabytes from
> > +the start of the kernel image. This is to allow the kernel to map the
> > +blob using a single section mapping in the initial page tables.
>
> I've seen people put firmware for some peripherals into the device tree,
> so that a device driver can grab a blob from there and load it into the
> device, rather than calling request_firmware() which would fail if the
> OS running on the system does not contain the blob. If such firmware is
> too large, you end up violating the 2 MB limit you impose here.
>
> Should we keep that limit and declare those use cases as invalid, or
> should we try to make the boot protocol more flexible?
>
> > diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
> > new file mode 100644
> > index 0000000..d766493
> > --- /dev/null
> > +++ b/arch/arm64/include/asm/setup.h
> > @@ -0,0 +1,26 @@
> > +#ifndef __ASM_SETUP_H
> > +#define __ASM_SETUP_H
> > +
> > +#include <linux/types.h>
> > +
> > +#define COMMAND_LINE_SIZE 1024
> > +
> > +#endif
>
> Is this necessary? The asm-generic version of this file allows 512 bytes,
> which seems plenty.
Chrome OS on my system today uses a 553 character cmdline, in particular
because some of the device mapper arguments are in there (since we boot without
ramdisk). It adds up quickly.
I suggest keeping it common with x86 since those limits are what people
will be used to (2048).
-Olof
next prev parent reply other threads:[~2012-08-15 17:06 UTC|newest]
Thread overview: 170+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-14 17:52 [PATCH v2 00/31] AArch64 Linux kernel port Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 01/31] arm64: Assembly macros and definitions Catalin Marinas
2012-08-15 12:57 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 02/31] arm64: Kernel booting and initialisation Catalin Marinas
2012-08-14 23:06 ` Olof Johansson
2012-08-15 17:37 ` Catalin Marinas
2012-08-15 19:03 ` Olof Johansson
2012-08-15 19:53 ` Catalin Marinas
2012-08-15 13:20 ` Arnd Bergmann
2012-08-15 17:06 ` Olof Johansson [this message]
2012-08-16 12:53 ` Catalin Marinas
2012-08-16 18:59 ` Nicolas Pitre
2012-08-17 11:20 ` Arnd Bergmann
2012-08-17 13:45 ` Catalin Marinas
2012-08-17 18:21 ` Nicolas Pitre
2012-08-17 8:56 ` Tony Lindgren
2012-08-17 9:41 ` Santosh Shilimkar
2012-08-17 10:05 ` Catalin Marinas
2012-08-17 10:10 ` Shilimkar, Santosh
2012-08-17 13:13 ` Tony Lindgren
2012-08-17 13:48 ` Catalin Marinas
2012-08-24 9:50 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 03/31] arm64: Exception handling Catalin Marinas
2012-08-14 23:29 ` Olof Johansson
2012-08-14 23:47 ` Thomas Gleixner
2012-08-15 13:03 ` Arnd Bergmann
2012-08-16 10:05 ` Will Deacon
2012-08-16 11:54 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 04/31] arm64: MMU definitions Catalin Marinas
2012-08-15 13:30 ` Arnd Bergmann
2012-08-15 13:39 ` Catalin Marinas
2012-08-15 16:34 ` Geert Uytterhoeven
2012-08-15 16:45 ` Catalin Marinas
2012-08-17 9:04 ` Tony Lindgren
2012-08-17 9:21 ` Catalin Marinas
2012-08-17 9:38 ` Tony Lindgren
2012-08-14 17:52 ` [PATCH v2 05/31] arm64: MMU initialisation Catalin Marinas
2012-08-15 13:45 ` Arnd Bergmann
2012-08-17 10:06 ` Santosh Shilimkar
2012-08-17 10:15 ` Catalin Marinas
2012-08-17 10:25 ` Shilimkar, Santosh
2012-08-14 17:52 ` [PATCH v2 06/31] arm64: MMU fault handling and page table management Catalin Marinas
2012-08-15 13:47 ` Arnd Bergmann
2012-08-17 16:07 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 07/31] arm64: Process management Catalin Marinas
2012-08-14 23:50 ` Olof Johansson
2012-09-14 17:33 ` Catalin Marinas
2012-09-16 0:29 ` Olof Johansson
2012-08-15 13:53 ` Arnd Bergmann
2012-08-17 16:15 ` Catalin Marinas
2012-08-16 15:09 ` Tobias Klauser
2012-08-14 17:52 ` [PATCH v2 08/31] arm64: CPU support Catalin Marinas
2012-08-15 0:10 ` Olof Johansson
2012-08-20 15:57 ` Catalin Marinas
2012-08-20 20:47 ` Arnd Bergmann
2012-08-21 9:50 ` Catalin Marinas
2012-09-14 17:38 ` Catalin Marinas
2012-08-15 13:56 ` Arnd Bergmann
2012-08-20 16:00 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 09/31] arm64: Cache maintenance routines Catalin Marinas
2012-08-17 9:57 ` Santosh Shilimkar
2012-08-17 10:07 ` Catalin Marinas
2012-08-17 10:12 ` Shilimkar, Santosh
2012-08-14 17:52 ` [PATCH v2 10/31] arm64: TLB maintenance functionality Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 11/31] arm64: IRQ handling Catalin Marinas
2012-08-14 23:22 ` Aaro Koskinen
2012-08-14 17:52 ` [PATCH v2 12/31] arm64: Atomic operations Catalin Marinas
2012-08-15 0:21 ` Olof Johansson
2012-08-14 17:52 ` [PATCH v2 13/31] arm64: Device specific operations Catalin Marinas
2012-08-15 0:33 ` Olof Johansson
2012-09-14 17:29 ` Catalin Marinas
2012-09-14 17:31 ` Arnd Bergmann
2012-09-14 17:39 ` Catalin Marinas
2012-09-16 0:28 ` Olof Johansson
2012-08-15 16:13 ` Arnd Bergmann
2012-08-17 9:19 ` Tony Lindgren
2012-08-14 17:52 ` [PATCH v2 14/31] arm64: DMA mapping API Catalin Marinas
2012-08-15 0:40 ` Olof Johansson
2012-08-21 13:05 ` Catalin Marinas
2012-08-15 16:16 ` Arnd Bergmann
2012-08-21 12:59 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 15/31] arm64: SMP support Catalin Marinas
2012-08-15 0:49 ` Olof Johansson
2012-08-15 13:04 ` Arnd Bergmann
2012-08-17 9:21 ` Tony Lindgren
2012-08-17 9:32 ` Catalin Marinas
2012-08-17 9:39 ` Tony Lindgren
2012-08-14 17:52 ` [PATCH v2 16/31] arm64: ELF definitions Catalin Marinas
2012-08-15 14:15 ` Arnd Bergmann
2012-08-16 10:23 ` Will Deacon
2012-08-16 12:37 ` Arnd Bergmann
2012-08-21 16:06 ` Catalin Marinas
2012-08-21 18:17 ` Geert Uytterhoeven
2012-08-21 18:27 ` Catalin Marinas
2012-08-21 18:53 ` Mike Frysinger
2012-08-21 20:17 ` Arnd Bergmann
2012-09-05 19:56 ` Chris Metcalf
2012-08-14 17:52 ` [PATCH v2 17/31] arm64: System calls handling Catalin Marinas
2012-08-15 14:22 ` Arnd Bergmann
2012-08-21 17:51 ` Catalin Marinas
2012-08-21 20:14 ` Arnd Bergmann
2012-08-21 22:01 ` Catalin Marinas
2012-08-22 7:56 ` Arnd Bergmann
2012-08-22 10:29 ` Catalin Marinas
2012-08-22 12:27 ` Arnd Bergmann
2012-08-22 17:13 ` Catalin Marinas
2012-09-03 11:48 ` Catalin Marinas
2012-09-03 12:39 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 18/31] arm64: VDSO support Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 19/31] arm64: Signal handling support Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 20/31] arm64: User access library functions Catalin Marinas
2012-08-15 14:49 ` [PATCH v2 20/31] arm64: User access library function Arnd Bergmann
2012-09-03 12:58 ` Catalin Marinas
2012-09-05 19:13 ` Russell King - ARM Linux
2012-09-05 21:01 ` Catalin Marinas
2012-09-05 21:05 ` Russell King - ARM Linux
2012-09-06 8:36 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 21/31] arm64: 32-bit (compat) applications support Catalin Marinas
2012-08-15 14:34 ` Arnd Bergmann
2012-08-16 10:28 ` Will Deacon
2012-08-16 12:39 ` Arnd Bergmann
2012-08-23 6:46 ` PER_LINUX32, Was: " Arnd Bergmann
2012-08-23 10:42 ` Catalin Marinas
2012-08-28 18:28 ` Jiri Kosina
2012-08-24 10:43 ` Catalin Marinas
2012-08-26 4:49 ` Arnd Bergmann
2012-08-20 10:53 ` Pavel Machek
2012-08-20 20:34 ` Arnd Bergmann
2012-08-21 10:28 ` Pavel Machek
2012-08-14 17:52 ` [PATCH v2 22/31] arm64: Floating point and SIMD Catalin Marinas
2012-08-15 14:35 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 23/31] arm64: Debugging support Catalin Marinas
2012-08-15 15:07 ` Arnd Bergmann
2012-08-16 10:47 ` Will Deacon
2012-08-16 12:49 ` Arnd Bergmann
2012-08-17 7:06 ` Arnd Bergmann
2012-08-20 9:07 ` Will Deacon
2012-08-20 9:27 ` Will Deacon
2012-08-20 20:10 ` Arnd Bergmann
2012-08-21 8:58 ` Will Deacon
2012-08-14 17:52 ` [PATCH v2 24/31] arm64: Add support for /proc/sys/debug/exception-trace Catalin Marinas
2012-08-15 15:08 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 25/31] arm64: Performance counters support Catalin Marinas
2012-08-15 15:11 ` Arnd Bergmann
2012-08-16 10:51 ` Will Deacon
2012-08-14 17:52 ` [PATCH v2 26/31] arm64: Miscellaneous library functions Catalin Marinas
2012-08-15 15:21 ` Arnd Bergmann
2012-08-16 10:57 ` Will Deacon
2012-08-16 13:00 ` Arnd Bergmann
2012-08-16 14:11 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 27/31] arm64: Loadable modules Catalin Marinas
2012-08-15 15:23 ` Arnd Bergmann
2012-08-15 15:35 ` Catalin Marinas
2012-08-15 16:16 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 28/31] arm64: Generic timers support Catalin Marinas
2012-08-15 15:52 ` Arnd Bergmann
2012-08-16 12:40 ` Linus Walleij
2012-08-17 9:29 ` Tony Lindgren
2012-08-17 10:21 ` Santosh Shilimkar
2012-08-21 19:20 ` Christopher Covington
2012-08-14 17:52 ` [PATCH v2 29/31] arm64: Miscellaneous header files Catalin Marinas
2012-08-15 15:56 ` Arnd Bergmann
2012-08-14 17:52 ` [PATCH v2 30/31] arm64: Build infrastructure Catalin Marinas
2012-08-14 21:01 ` Sam Ravnborg
2012-08-15 16:07 ` Arnd Bergmann
2012-08-17 9:32 ` Tony Lindgren
2012-08-17 9:46 ` Catalin Marinas
2012-08-14 17:52 ` [PATCH v2 31/31] arm64: MAINTAINERS update Catalin Marinas
2012-08-15 15:57 ` Arnd Bergmann
2012-08-17 9:36 ` [PATCH v2 00/31] AArch64 Linux kernel port Tony Lindgren
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