From: robert.jarzmik@free•fr (Robert Jarzmik)
To: linux-arm-kernel@lists•infradead.org
Subject: Initrd and 2.6.33 curious behaviour
Date: Thu, 27 May 2010 14:00:34 +0200 [thread overview]
Message-ID: <87pr0hy2ot.fsf@free.fr> (raw)
In-Reply-To: <87hblz2alm.fsf@free.fr> (Robert Jarzmik's message of "Sun\, 23 May 2010 12\:09\:25 +0200")
I have made some progress.
I have traced that :
- after the bootloader has disabled the MMU, disabled the caches, quiesced
the DMAs and masked the interrupts, and just before the final jump to the
kernel first instruction :
=> the first u32 at physical address 0xa0508000 is 1f:8b:08:08
=> this is the correct begining of my initrd.gz
In function setup_arch(), just after paging_init(mdesc), I read the value again
with a "rjk = *((unsigned int *)(phys_to_virt(0xa0508000)));", and it has
changed to 10:00:00:a0.
Now, I would need some help to trace this memory location before
paging_init(). My current understanding is that before paging_init(), the MMU is
set by __create_page_tables(). The mapping doesn't cover the initrd area.
If I was to be able to watch this area, I would need to :
- amend __create_page_tables(), and add a mapping for the 0xa0508000 area (1MB
is enough)
- read the value of the u32 at physical address 0xa0508000 from this mapping
- printk the stored value at the end of setup_arch()
The questions I have are :
- is this the right approach ?
- which virtual address space can I use for my mapping
--
Robert
prev parent reply other threads:[~2010-05-27 12:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-21 20:27 Initrd and 2.6.33 curious behaviour Robert Jarzmik
2010-05-21 20:43 ` Russell King - ARM Linux
2010-05-22 9:36 ` Robert Jarzmik
2010-05-22 9:37 ` Robert Jarzmik
2010-05-22 9:46 ` Russell King - ARM Linux
2010-05-23 0:23 ` Robert Jarzmik
2010-05-23 9:01 ` Russell King - ARM Linux
2010-05-23 10:09 ` Robert Jarzmik
2010-05-24 19:22 ` Robert Jarzmik
2010-05-27 12:00 ` Robert Jarzmik [this message]
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