From: per.xx.fransson@stericsson•com (Per Fransson)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 0/8] Initial implementation of kdump for ARM
Date: Mon, 5 Jul 2010 12:01:06 +0200 [thread overview]
Message-ID: <4C31AD62.6070805@stericsson.com> (raw)
In-Reply-To: <20100705082835.GA32178@gw.healthdatacare.com>
On 07/05/2010 10:28 AM, Mika Westerberg wrote:
>>
>> I have a question regarding these patches. It seems to me that the kexec
>> will be done with the MMU left on for the ARMv7 case. Looking at the
>> code in the cpu_arm926_reset() routine in arch/arm/mm/proc-arm926.S this
>> is not the case there. Instead, the MMU is turned off and the last
>> instruction that is fetched using the virtual address mapping is a jump
>> to a physical address.
>
> This seems to be the case for both ARMv6 and ARMv7. I don't know
> why the MMU is not switched off there. Anyway, I've been testing
> this on ARMv7 and at least for panic kernel it works even when MMU
> is left on (didn't check but maybe the decompressor disables that
> before jumping to the kernel).
>
In machine_kexec an identity mapping is set up for the user space part
of the virtual address space, through a call to setup_mm_for_reboot(). I
believe this mapping is only necessary because the MMU is kept on and if
the kexec is done to facilitate the collection of a dump it would be
nice if a large part of the page table for the crashing context has not
been corrupted. Don't you agree?
>> Shouldn't this be handled as consistently as possible for the different
>> ARM sub-archs?
>
> Yes, I guess. I'm still wondering why this hasn't been fixed already?
Can't help you there, I'm afraid.
Regards,
Per
next prev parent reply other threads:[~2010-07-05 10:01 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-05 6:54 [PATCH v2 0/8] Initial implementation of kdump for ARM Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 1/8] arm: kdump: reserve memory for crashkernel Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 2/8] arm: kdump: implement crash_setup_regs() Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 3/8] arm: kdump: implement machine_crash_shutdown() Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 4/8] arm: kdump: skip indirection page when crashing Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 5/8] arm: kdump: implement copy_oldmem_page() Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 6/8] arm: allow passing an ELF64 header to elf_check_arch() Mika Westerberg
2010-05-10 11:20 ` Russell King - ARM Linux
2010-05-10 12:09 ` Mika Westerberg
2010-05-10 12:21 ` Russell King - ARM Linux
2010-05-11 7:17 ` Mika Westerberg
2010-07-16 8:14 ` Mika Westerberg
2010-08-25 2:40 ` Lei Wen
2010-08-25 12:29 ` Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 7/8] arm: kdump: add support for elfcorehdr= parameter Mika Westerberg
2010-05-05 6:54 ` [PATCH v2 8/8] arm: kdump: add CONFIG_CRASH_DUMP Kconfig option Mika Westerberg
2010-05-25 8:19 ` [PATCH v2 0/8] Initial implementation of kdump for ARM Mika Westerberg
2010-06-11 6:36 ` Mika Westerberg
2010-07-02 12:48 ` Per Fransson
2010-07-05 8:28 ` Mika Westerberg
2010-07-05 10:01 ` Per Fransson [this message]
2010-07-05 10:18 ` Russell King - ARM Linux
2010-07-05 10:34 ` Per Fransson
2010-07-05 11:31 ` Mika Westerberg
2010-07-05 12:04 ` Per Fransson
2010-07-05 13:55 ` Russell King - ARM Linux
2010-07-05 14:05 ` Per Fransson
2010-07-05 14:19 ` Russell King - ARM Linux
2010-07-05 15:37 ` Per Fransson
2010-07-05 16:08 ` Nicolas Pitre
2010-07-05 18:14 ` Russell King - ARM Linux
2010-07-06 8:30 ` Per Fransson
2010-07-07 7:29 ` Mika Westerberg
2010-07-08 8:52 ` Per Fransson
2010-07-12 8:20 ` Mika Westerberg
2010-07-09 3:38 ` Simon Horman
2010-07-09 8:19 ` Per Fransson
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