From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Ingo Molnar <mingo@elte.hu>
Cc: Petr Tesarik <ptesarik@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Fenghua Yu <fenghua.yu@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Paul Mundt <lethal@linux-sh.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
linux-kernel@vger.kernel.org,
Arjan van de Ven <arjan@infradead.org>,
Dave Jones <davej@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 00/10] Enhance /dev/mem to allow read/write of arbitrary physical addresses
Date: Fri, 17 Jun 2011 10:41:25 +0100 [thread overview]
Message-ID: <20110617094125.GE32629@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20110617093032.GA19235@elte.hu>
On Fri, Jun 17, 2011 at 11:30:32AM +0200, Ingo Molnar wrote:
> I'm aware of these current /dev/mem uses:
>
> - Xorg maps below 4G non-RAM addresses and the video BIOS
>
> - It used to have some debugging role but these days kexec and kgdb
> has largely taken over that role - partly due to the 4G limit.
>
> - there's some really horrible out-of-tree drivers that do mmap()s
> via /dev/mem, those should be fixed if they want to move beyond
> 4G: their char device should be mmap()able.
>
> - all distro kernel's i'm aware of use CONFIG_STRICT_DEVMEM=y, which
> restricts /dev/mem to non-RAM pages of physical memory.
> [ With the sad inclusion of the first 1MB, which Xorg needs. ]
There's another use case for /dev/mem:
- debugging via devmem2 on embedded platforms, where you want to be able
to boot a kernel, and then peek and poke at MMIO registers either to
verify register values or test things out.
next prev parent reply other threads:[~2011-06-17 9:46 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-17 8:38 Petr Tesarik
2011-06-17 8:43 ` [PATCH 01/10] Return EOF on out-of-bounds read from /dev/mem Petr Tesarik
2011-06-17 8:44 ` [PATCH 02/10] (un)xlate_dev_mem_ptr: use phys_addr_t for the @phys parameter Petr Tesarik
2011-06-17 8:45 ` [PATCH 03/10] x86: translate highmem /dev/mem pointers Petr Tesarik
2011-06-17 8:45 ` [PATCH 04/10] ia64: change xlate_dev_mem_ptr's argument to phys_addr_t Petr Tesarik
2011-06-17 8:45 ` [PATCH 05/10] valid_phys_addr_range: use phys_addr_t for the @addr parameter Petr Tesarik
2011-06-17 8:46 ` [PATCH 06/10] sh: change valid_phys_addr_range's @addr param to phys_addr_t Petr Tesarik
2011-06-17 8:46 ` [PATCH 07/10] arm: " Petr Tesarik
2011-06-17 8:47 ` [PATCH 08/10] ia64: " Petr Tesarik
2011-06-17 8:48 ` [PATCH 09/10] x86: provide arch-specific valid_phys_addr_range() Petr Tesarik
2011-06-17 8:48 ` [PATCH 10/10] Allow reading/writing all memory through /dev/mem Petr Tesarik
2011-06-17 9:30 ` [PATCH 00/10] Enhance /dev/mem to allow read/write of arbitrary physical addresses Ingo Molnar
2011-06-17 9:41 ` Russell King - ARM Linux [this message]
2011-06-17 9:55 ` Petr Tesarik
2011-06-20 2:42 ` Américo Wang
2011-06-27 7:46 ` Petr Tesarik
2011-06-19 23:02 ` Ryan Mallon
2011-06-19 23:44 ` H. Peter Anvin
2011-06-20 7:41 ` Ingo Molnar
2011-06-20 15:59 ` H. Peter Anvin
2011-06-20 16:40 ` Ingo Molnar
2011-06-20 16:44 ` H. Peter Anvin
2011-06-21 6:55 ` Srivatsa Vaddagiri
2011-06-20 0:42 ` Matthew Wilcox
2011-06-20 0:46 ` Ryan Mallon
2011-06-20 0:52 ` Matthew Wilcox
2011-06-20 1:02 ` Ryan Mallon
2011-06-20 7:31 ` Ingo Molnar
2011-06-20 8:03 ` Ryan Mallon
2011-06-20 17:10 ` Ray Lee
2011-06-29 9:05 ` Petr Tesarik
2011-07-01 12:58 ` Ingo Molnar
2011-07-01 13:43 ` Petr Tesarik
2011-07-01 13:47 ` Christoph Hellwig
2011-07-01 14:37 ` Ingo Molnar
2011-07-01 14:41 ` Christoph Hellwig
2011-07-01 14:46 ` Ingo Molnar
2011-07-01 14:54 ` Petr Tesarik
2011-07-01 15:36 ` Ingo Molnar
2011-07-01 16:00 ` H. Peter Anvin
2011-07-01 16:13 ` Ingo Molnar
2011-07-01 19:34 ` Petr Tesarik
2011-07-01 19:56 ` Ingo Molnar
2011-07-01 20:44 ` Petr Tesarik
2011-07-03 19:46 ` Ingo Molnar
2011-07-05 17:49 ` Matthew Garrett
2011-07-05 17:56 ` H. Peter Anvin
2011-07-05 22:34 ` H. Peter Anvin
2011-06-20 13:24 Dave Anderson
2011-06-21 2:52 ` Cong Wang
2011-06-21 13:03 ` Dave Anderson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110617094125.GE32629@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=akpm@linux-foundation.org \
--cc=arjan@infradead.org \
--cc=davej@redhat.com \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=lethal@linux-sh.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=mingo@redhat.com \
--cc=ptesarik@suse.cz \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome