From: "Pali Rohár" <pali.rohar@gmail.com> To: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: "Laura Abbott" <lauraa@codeaurora.org>, "Grant Likely" <grant.likely@linaro.org>, "Rob Herring" <robherring2@gmail.com>, "Will Deacon" <will.deacon@arm.com>, "Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>, "Sebastian Reichel" <sre@debian.org>, "Pavel Machek" <pavel@ucw.cz>, "Tony Lindgren" <tony@atomide.com>, "Andreas Färber" <afaerber@suse.de>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Subject: Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Date: Tue, 7 Jul 2015 13:58:19 +0200 [thread overview] Message-ID: <20150707115819.GF12087@pali> (raw) In-Reply-To: <20150707113213.GC7576@n2100.arm.linux.org.uk> On Tuesday 07 July 2015 12:32:13 Russell King - ARM Linux wrote: > On Mon, Jul 06, 2015 at 10:26:13PM +0200, Pali Rohár wrote: > > Legacy bootloaders can pass additional information for kernel or legacy > > userspace applications. When booting DT kernel then ATAGs structure is not > > more visible after running kernel uncompress code. This patch stores full > > ATAGs structure into DT "/chosen/linux,atags" entry, so kernel can later > > reuse it and export via /proc/atags to userspace. > > I think you need to go through your commit messages and improve them, > especially the ones with "TODO" in them. As long as there's still things > to be done, they're obviously not ready for merging. > I know, in cover letter email I wrote that documentation is not ready... I send patches for review and comments (like yours). I think it is still better to send something and mark it as incomplete. It could prevent to work on something which will be again rewritten... > Moreover, exporting the ATAGS is questionable, even _if_ there are non- > kexec programs making use of this. The ATAGs have _never_ been exported > to userspace when kexec disabled is the kernel - it was introduced for > kexec, and has always had this: > > config ATAGS_PROC > bool "Export atags in procfs" > depends on ATAGS && KEXEC > default y > > Now, the fact that someone decided to start using it is pretty sad, > because it means that if you disable KEXEC, userspace breaks. That's > not a kernel regression in any shape or form, because /proc/atags has > never been there without KEXEC enabled. That's a userspace bug, plain > and simple. > > Given that, I'm in two minds about whether to accept the last two > patches which make this more than just "for KEXEC use to enable a KEXEC > kernel to be booted." > > Had it been provided without the KEXEC conditional, then I don't have > a problem with these two patches. > I understand it. Nokia originally invented their own entries in /proc/ which export needed ATAGs from kernel in human-readable form, but all those entries were non-standard and specific for Nokia's kernels. Do you have some other idea how to provide ATAGs information created dynamically by legacy closed proprietary bootloader to userspace from DT booted kernel? Anyway, for supporting kexec (with passing ATAGs) it is needed to have working /proc/atags file, right? > It also sets a precedent: by adding this into DT, it is creating a new > DT ABI as well, and we'll end up seeing dts files with an ATAG block > patched into them. > > Are the ATAGs at a fixed address on the N900? Yes, in board-rx51.c is: .atag_offset = 0x100 and Nokia Bootloader (proprietary) store them to that address. > Can that be handled in > some kind of legacy file for the N900 which calls save_atags() on it, so > we don't end up introducing yet more stuff that we have to maintain into > the distant future? If not, what about copying a known working atag > structure into a legacy file for the N900? > I already asked question if it is possible to read ATAGs from DT booted kernel. And somebody (do not remember who) wrote to ML, that it is not possible and it can be done in that uncompress code. -- Pali Rohár pali.rohar@gmail.com
WARNING: multiple messages have this Message-ID (diff)
From: pali.rohar@gmail.com (Pali Rohár) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Date: Tue, 7 Jul 2015 13:58:19 +0200 [thread overview] Message-ID: <20150707115819.GF12087@pali> (raw) In-Reply-To: <20150707113213.GC7576@n2100.arm.linux.org.uk> On Tuesday 07 July 2015 12:32:13 Russell King - ARM Linux wrote: > On Mon, Jul 06, 2015 at 10:26:13PM +0200, Pali Roh?r wrote: > > Legacy bootloaders can pass additional information for kernel or legacy > > userspace applications. When booting DT kernel then ATAGs structure is not > > more visible after running kernel uncompress code. This patch stores full > > ATAGs structure into DT "/chosen/linux,atags" entry, so kernel can later > > reuse it and export via /proc/atags to userspace. > > I think you need to go through your commit messages and improve them, > especially the ones with "TODO" in them. As long as there's still things > to be done, they're obviously not ready for merging. > I know, in cover letter email I wrote that documentation is not ready... I send patches for review and comments (like yours). I think it is still better to send something and mark it as incomplete. It could prevent to work on something which will be again rewritten... > Moreover, exporting the ATAGS is questionable, even _if_ there are non- > kexec programs making use of this. The ATAGs have _never_ been exported > to userspace when kexec disabled is the kernel - it was introduced for > kexec, and has always had this: > > config ATAGS_PROC > bool "Export atags in procfs" > depends on ATAGS && KEXEC > default y > > Now, the fact that someone decided to start using it is pretty sad, > because it means that if you disable KEXEC, userspace breaks. That's > not a kernel regression in any shape or form, because /proc/atags has > never been there without KEXEC enabled. That's a userspace bug, plain > and simple. > > Given that, I'm in two minds about whether to accept the last two > patches which make this more than just "for KEXEC use to enable a KEXEC > kernel to be booted." > > Had it been provided without the KEXEC conditional, then I don't have > a problem with these two patches. > I understand it. Nokia originally invented their own entries in /proc/ which export needed ATAGs from kernel in human-readable form, but all those entries were non-standard and specific for Nokia's kernels. Do you have some other idea how to provide ATAGs information created dynamically by legacy closed proprietary bootloader to userspace from DT booted kernel? Anyway, for supporting kexec (with passing ATAGs) it is needed to have working /proc/atags file, right? > It also sets a precedent: by adding this into DT, it is creating a new > DT ABI as well, and we'll end up seeing dts files with an ATAG block > patched into them. > > Are the ATAGs at a fixed address on the N900? Yes, in board-rx51.c is: .atag_offset = 0x100 and Nokia Bootloader (proprietary) store them to that address. > Can that be handled in > some kind of legacy file for the N900 which calls save_atags() on it, so > we don't end up introducing yet more stuff that we have to maintain into > the distant future? If not, what about copying a known working atag > structure into a legacy file for the N900? > I already asked question if it is possible to read ATAGs from DT booted kernel. And somebody (do not remember who) wrote to ML, that it is not possible and it can be done in that uncompress code. -- Pali Roh?r pali.rohar at gmail.com
next prev parent reply other threads:[~2015-07-07 11:59 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 [this message] 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 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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