From: Arnd Bergmann <arnd@arndb.de>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
"Russell King - ARM Linux" <linux@arm.linux.org.uk>,
"Pali Rohár" <pali.rohar@gmail.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>,
"Laura Abbott" <lauraa@codeaurora.org>,
"Tony Lindgren" <tony@atomide.com>,
"Sebastian Reichel" <sre@debian.org>,
"Will Deacon" <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
"Rob Herring" <robherring2@gmail.com>,
"Pavel Machek" <pavel@ucw.cz>,
"Grant Likely" <grant.likely@linaro.org>,
linux-omap@vger.kernel.org,
"Frank Rowand" <frowand.list@gmail.com>,
"Andreas Färber" <afaerber@suse.de>
Subject: Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry
Date: Sat, 28 Nov 2015 13:27:07 +0100 [thread overview]
Message-ID: <2565382.eR6yg1spIk@wuerfel> (raw)
In-Reply-To: <alpine.LFD.2.20.1511271817230.22569@knanqh.ubzr>
On Friday 27 November 2015 18:28:50 Nicolas Pitre wrote:
> On Fri, 27 Nov 2015, Arnd Bergmann wrote:
>
> > I don't mind creating the /proc/atags compatibility hack from the kernel
> > for a DT based N700 kernel, as long as we limit it as much as we can
> > to the machines that need it. Leaving a board file for the N700 in place
> > that contains the procfs code (and not much more) seems reasonable
> > here, as we are talking about a board specific hack and the whole point
> > appears to be running unmodified user space.
> >
> > Regarding how to get the data into the kernel in the first place, my
> > preferred choice would still be to have an intermediate bootloader
> > such as pxa-impedance-matcher, but I won't complain if others are
> > happy enough about putting it into the ATAGS compat code we already
> > have, as long as it's limited to the boards we know need it.
>
> Assuming you have a N700 board file for special procfs code, then why
> not getting at the atags in memory where the bootloader has put them
> directly from that same board file? This way it'll really be limited to
> the board we know needs it and the special exception will be contained
> to that one file. Amongst the machine specific hooks, there is one that
> gets invoked early during boot before those atags are overwritten.
I didn't realize this was possible, as we don't know the atags pointer
when we instead get a DTB pointer. However you are right: the board
file knows exactly that the atag_offset is 0x100, so we can grab it
from there, and that will make the implementation really easy and
contained to a single file that has access to the atags and that
can create the /proc/atags file for it.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
To: Nicolas Pitre <nicolas.pitre-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
"Russell King - ARM Linux"
<linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
"Pali Rohár" <pali.rohar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"Ivaylo Dimitrov"
<ivo.g.dimitrov.75-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Laura Abbott" <lauraa-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
"Tony Lindgren" <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>,
"Sebastian Reichel" <sre-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>,
"Will Deacon" <will.deacon-5wv7dgnIgG8@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"Rob Herring"
<robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Pavel Machek" <pavel-+ZI9xUNit7I@public.gmane.org>,
"Grant Likely"
<grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"Frank Rowand"
<frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Andreas Färber" <afaerber-l3A5Bk7waGM@public.gmane.org>
Subject: Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry
Date: Sat, 28 Nov 2015 13:27:07 +0100 [thread overview]
Message-ID: <2565382.eR6yg1spIk@wuerfel> (raw)
In-Reply-To: <alpine.LFD.2.20.1511271817230.22569-fMhRO7WWcppj+hNMo8g0rg@public.gmane.org>
On Friday 27 November 2015 18:28:50 Nicolas Pitre wrote:
> On Fri, 27 Nov 2015, Arnd Bergmann wrote:
>
> > I don't mind creating the /proc/atags compatibility hack from the kernel
> > for a DT based N700 kernel, as long as we limit it as much as we can
> > to the machines that need it. Leaving a board file for the N700 in place
> > that contains the procfs code (and not much more) seems reasonable
> > here, as we are talking about a board specific hack and the whole point
> > appears to be running unmodified user space.
> >
> > Regarding how to get the data into the kernel in the first place, my
> > preferred choice would still be to have an intermediate bootloader
> > such as pxa-impedance-matcher, but I won't complain if others are
> > happy enough about putting it into the ATAGS compat code we already
> > have, as long as it's limited to the boards we know need it.
>
> Assuming you have a N700 board file for special procfs code, then why
> not getting at the atags in memory where the bootloader has put them
> directly from that same board file? This way it'll really be limited to
> the board we know needs it and the special exception will be contained
> to that one file. Amongst the machine specific hooks, there is one that
> gets invoked early during boot before those atags are overwritten.
I didn't realize this was possible, as we don't know the atags pointer
when we instead get a DTB pointer. However you are right: the board
file knows exactly that the atag_offset is 0x100, so we can grab it
from there, and that will make the implementation really easy and
contained to a single file that has access to the atags and that
can create the /proc/atags file for it.
Arnd
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WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry
Date: Sat, 28 Nov 2015 13:27:07 +0100 [thread overview]
Message-ID: <2565382.eR6yg1spIk@wuerfel> (raw)
In-Reply-To: <alpine.LFD.2.20.1511271817230.22569@knanqh.ubzr>
On Friday 27 November 2015 18:28:50 Nicolas Pitre wrote:
> On Fri, 27 Nov 2015, Arnd Bergmann wrote:
>
> > I don't mind creating the /proc/atags compatibility hack from the kernel
> > for a DT based N700 kernel, as long as we limit it as much as we can
> > to the machines that need it. Leaving a board file for the N700 in place
> > that contains the procfs code (and not much more) seems reasonable
> > here, as we are talking about a board specific hack and the whole point
> > appears to be running unmodified user space.
> >
> > Regarding how to get the data into the kernel in the first place, my
> > preferred choice would still be to have an intermediate bootloader
> > such as pxa-impedance-matcher, but I won't complain if others are
> > happy enough about putting it into the ATAGS compat code we already
> > have, as long as it's limited to the boards we know need it.
>
> Assuming you have a N700 board file for special procfs code, then why
> not getting at the atags in memory where the bootloader has put them
> directly from that same board file? This way it'll really be limited to
> the board we know needs it and the special exception will be contained
> to that one file. Amongst the machine specific hooks, there is one that
> gets invoked early during boot before those atags are overwritten.
I didn't realize this was possible, as we don't know the atags pointer
when we instead get a DTB pointer. However you are right: the board
file knows exactly that the atag_offset is 0x100, so we can grab it
from there, and that will make the implementation really easy and
contained to a single file that has access to the atags and that
can create the /proc/atags file for it.
Arnd
next prev parent reply other threads:[~2015-11-28 12:27 UTC|newest]
Thread overview: 160+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 20:26 [PATCH 0/5] ATAGs to DT patches Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-07-06 20:26 ` [PATCH 1/5] arm: devtree: Set system_rev from DT "/revision" Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-12-24 19:02 ` Pali Rohár
2015-12-24 19:02 ` Pali Rohár
2015-12-24 19:02 ` Pali Rohár
2015-12-28 21:01 ` Frank Rowand
2015-12-28 21:01 ` Frank Rowand
2015-12-28 21:01 ` Frank Rowand
2015-12-28 22:27 ` Arnd Bergmann
2015-12-28 22:27 ` Arnd Bergmann
2015-12-28 22:27 ` Arnd Bergmann
2016-01-05 11:37 ` Pali Rohár
2016-01-05 11:37 ` Pali Rohár
2016-01-05 11:37 ` Pali Rohár
2016-01-05 11:37 ` Pali Rohár
2016-01-05 11:45 ` Arnd Bergmann
2016-01-05 11:45 ` Arnd Bergmann
2016-01-05 11:45 ` Arnd Bergmann
2016-02-05 18:15 ` [PATCH] ARM: RX51: Set system_rev from ATAGS Ivaylo Dimitrov
2016-02-05 18:15 ` Ivaylo Dimitrov
2016-02-08 20:48 ` Tony Lindgren
2016-02-08 20:48 ` Tony Lindgren
2016-02-08 21:10 ` Pali Rohár
2016-02-08 21:10 ` Pali Rohár
2016-02-09 16:17 ` Tony Lindgren
2016-02-09 16:17 ` Tony Lindgren
2016-02-10 18:23 ` [PATCH v1] " Ivaylo Dimitrov
2016-02-10 18:23 ` Ivaylo Dimitrov
2016-02-11 0:19 ` Tony Lindgren
2016-02-11 0:19 ` Tony Lindgren
2015-07-06 20:26 ` [PATCH 2/5] arm: boot: convert ATAG_REVISION to DT "/revision" entry Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-07-06 20:26 ` [PATCH 3/5] arm: atags: Fix declaration of function save_atags Pali Rohár
2015-07-06 20:26 ` Pali Rohár
2015-07-06 20:26 ` [PATCH 4/5] arm: devtree: Read ATAGs structure from DT "/chosen/linux,atags" entry Pali Rohár
2015-07-06 20:26 ` [PATCH 4/5] arm: devtree: Read ATAGs structure from DT "/chosen/linux, atags" entry Pali Rohár
2015-07-06 20:26 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-07-06 20:26 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-07-07 11:32 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Russell King - ARM Linux
2015-07-07 11:32 ` Russell King - ARM Linux
2015-07-07 11:58 ` Pali Rohár
2015-07-07 11:58 ` Pali Rohár
2015-07-13 13:19 ` Tony Lindgren
2015-07-13 13:19 ` Tony Lindgren
2015-10-12 20:16 ` Tony Lindgren
2015-10-12 20:16 ` Tony Lindgren
2015-10-12 20:25 ` Pali Rohár
2015-10-12 20:25 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-10-12 20:45 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Tony Lindgren
2015-10-12 20:45 ` Tony Lindgren
2015-10-13 14:37 ` Pali Rohár
2015-10-13 14:37 ` Pali Rohár
2015-11-05 11:40 ` Pali Rohár
2015-11-05 11:40 ` Pali Rohár
2015-11-05 16:17 ` Tony Lindgren
2015-11-05 16:17 ` Tony Lindgren
2015-11-12 1:10 ` Frank Rowand
2015-11-12 1:10 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Frank Rowand
2015-11-22 6:51 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pavel Machek
2015-11-22 6:51 ` Pavel Machek
2015-11-23 14:45 ` Pali Rohár
2015-11-23 14:45 ` Pali Rohár
2015-11-23 14:45 ` Pali Rohár
2015-11-25 18:16 ` Tony Lindgren
2015-11-25 18:16 ` Tony Lindgren
2015-11-25 18:16 ` Tony Lindgren
2015-11-25 19:48 ` Arnd Bergmann
2015-11-25 19:48 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-11-25 21:03 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Tony Lindgren
2015-11-25 21:03 ` Tony Lindgren
2015-11-25 21:03 ` Tony Lindgren
2015-11-25 21:29 ` Arnd Bergmann
2015-11-25 21:29 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-11-25 21:44 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-11-25 21:44 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-11-25 21:44 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-11-25 21:51 ` Arnd Bergmann
2015-11-25 21:51 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-11-25 22:00 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-11-25 22:00 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-11-26 4:19 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Frank Rowand
2015-11-26 4:19 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Frank Rowand
2015-11-26 9:07 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-11-26 9:07 ` Pali Rohár
2015-11-26 20:39 ` Tony Lindgren
2015-11-26 20:39 ` Tony Lindgren
2015-11-26 20:39 ` Tony Lindgren
2015-11-26 21:12 ` Ivaylo Dimitrov
2015-11-26 21:12 ` Ivaylo Dimitrov
2015-11-27 8:38 ` Pali Rohár
2015-11-27 8:38 ` Pali Rohár
2015-11-27 8:44 ` Michael Trimarchi
2015-11-27 8:44 ` Michael Trimarchi
2015-11-27 8:44 ` Michael Trimarchi
2015-11-27 8:52 ` Michael Trimarchi
2015-11-27 8:52 ` Michael Trimarchi
2015-11-27 14:51 ` Tony Lindgren
2015-11-27 14:51 ` Tony Lindgren
2015-11-27 13:27 ` Russell King - ARM Linux
2015-11-27 13:27 ` Russell King - ARM Linux
2015-11-27 19:51 ` Russell King - ARM Linux
2015-11-27 19:51 ` Russell King - ARM Linux
2015-11-27 19:51 ` Russell King - ARM Linux
2015-11-27 21:06 ` Arnd Bergmann
2015-11-27 21:06 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-11-27 23:28 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Nicolas Pitre
2015-11-27 23:28 ` Nicolas Pitre
2015-11-27 23:28 ` Nicolas Pitre
2015-11-28 12:27 ` Arnd Bergmann [this message]
2015-11-28 12:27 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-11-28 12:27 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Arnd Bergmann
2015-11-28 12:54 ` Russell King - ARM Linux
2015-11-28 12:54 ` Russell King - ARM Linux
2015-11-28 12:54 ` Russell King - ARM Linux
2015-11-28 12:33 ` Russell King - ARM Linux
2015-11-28 12:33 ` Russell King - ARM Linux
2015-11-28 17:34 ` Nicolas Pitre
2015-11-28 17:34 ` Nicolas Pitre
2015-11-28 21:02 ` Frank Rowand
2015-11-28 21:02 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Frank Rowand
2015-11-28 21:02 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Frank Rowand
2015-11-29 18:09 ` Russell King - ARM Linux
2015-11-29 18:09 ` Russell King - ARM Linux
2015-11-29 18:09 ` Russell King - ARM Linux
2015-11-29 18:19 ` Pali Rohár
2015-11-29 18:19 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-11-29 23:13 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Russell King - ARM Linux
2015-11-29 23:13 ` Russell King - ARM Linux
2015-11-30 0:09 ` Nicolas Pitre
2015-11-30 0:09 ` Nicolas Pitre
2015-11-30 0:15 ` Pali Rohár
2015-11-30 0:15 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Pali Rohár
2015-11-30 0:15 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Pali Rohár
2015-11-30 15:23 ` Tony Lindgren
2015-11-30 15:23 ` Tony Lindgren
2015-11-30 15:23 ` Tony Lindgren
2015-11-30 15:39 ` Pali Rohár
2015-11-30 15:39 ` Pali Rohár
2015-11-30 15:39 ` Pali Rohár
2015-11-30 16:09 ` Nicolas Pitre
2015-11-30 16:09 ` Nicolas Pitre
2015-12-15 9:33 ` Pali Rohár
2015-12-15 9:33 ` Pali Rohár
2015-12-15 11:04 ` Arnd Bergmann
2015-12-15 11:04 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux, atags" entry Arnd Bergmann
2015-12-15 12:20 ` [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Russell King - ARM Linux
2015-12-15 12:20 ` Russell King - ARM Linux
2015-12-15 17:24 ` Nicolas Pitre
2015-12-15 17:24 ` Nicolas Pitre
2015-12-15 17:24 ` Nicolas Pitre
2015-12-23 14:54 ` Ivaylo Dimitrov
2015-12-23 14:54 ` Ivaylo Dimitrov
2015-11-28 4:06 ` [PATCH 0/5] ATAGs to DT patches Frank Rowand
2015-11-28 4:06 ` Frank Rowand
2015-11-28 5:55 ` Frank Rowand
2015-11-28 5:55 ` Frank Rowand
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