From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Date: Thu, 17 Apr 2014 09:58:19 +0100 Subject: [U-Boot] [PATCH v3 00/13] ARMv7: add PSCI support to u-boot In-Reply-To: (Albert ARIBAUD's message of "Thu, 17 Apr 2014 09:34:24 +0100") References: <1392471397-2158-1-git-send-email-marc.zyngier@arm.com> <534EAB23.50800@arm.com> Message-ID: <87sipcwcwk.fsf@approximate.cambridge.arm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Thu, Apr 17 2014 at 9:34:24 am BST, Albert ARIBAUD wrote: > Hi Marc, > > On Wed, 16 Apr 2014 17:09:07 +0100, Marc Zyngier > wrote: > >> On 16/04/14 15:45, Albert ARIBAUD wrote: >> > Hi Marc, >> > >> > On Sat, 15 Feb 2014 13:36:24 +0000, Marc Zyngier >> > wrote: >> > >> >> PSCI is an ARM standard that provides a generic interface that >> >> supervisory software can use to manage power in the following >> >> situations: >> >> - Core idle management >> >> - CPU hotplug >> >> - big.LITTLE migration models >> >> - System shutdown and reset >> >> >> >> It basically allows the kernel to offload these tasks to the firmware, >> >> and rely on common kernel side code. >> >> >> >> More importantly, it gives a way to ensure that CPUs enter the kernel >> >> at the appropriate exception level (ie HYP mode, to allow the use of >> >> the virtualization extensions), even across events like CPUs being >> >> powered off/on or suspended. >> >> >> >> The main idea here is to turn some of the existing u-boot code into a >> >> separate section that can live in secure RAM (or a reserved page of >> >> memory), containing a secure monitor that will implement the PSCI >> >> operations. This code will still be alive when u-boot is long gone, >> >> hence the need for a piece of memory that will not be touched by the >> >> OS. >> >> >> >> This patch series contains 4 parts: >> >> - the first four patches are just bug fixes >> >> - the next two refactor the HYP/non-secure code to allow relocation >> >> in secure memory >> >> - the next four contain the generic PSCI code and DT infrastructure >> >> - the last three implement the CPU_ON method of the Allwinner A20 (aka sun7i). >> >> >> >> I realize the A20 u-boot code is not upstream yet (BTW is anyone >> >> actively working on that?), but hopefully that should give a good idea >> >> of how things are structured so far. The patches are against the >> >> mainline u-boot tree as of today, merged with the sunxi u-boot tree >> >> of the day and the first 10 patches will directly apply to mainline >> >> u-boot. >> >> >> >> As for using this code, it goes like this: >> >> sun7i# ext2load mmc 0:1 0x40008000 zImage ; ext2load mmc 0:1 0x60000000 sun7i-a20-cubietruck.dtb >> >> 2270120 bytes read in 117 ms (18.5 MiB/s) >> >> 9138 bytes read in 3 ms (2.9 MiB/s) >> >> sun7i# fdt addr 0x60000000 ; fdt resize ; fdt set ethernet0 mac-address "[5a fe b0 07 b0 07]" >> >> sun7i# setenv bootargs console=ttyS0,115200 earlyprintk ip=dhcp root=/dev/nfs nfsroot=/backup/a20_root,tcp >> >> sun7i# bootz 0x40008000 - 0x60000000 >> >> >> >> The kernel now boots in HYP mode, finds its secondary CPU without any >> >> SMP code present in the kernel, and runs KVM out of the box. >> >> I've been told the Xen/ARM guys managed to do the same fairly easily. >> >> >> >> This code has also been tested on a VExpress TC2, running KVM with all >> >> 5 CPUs, in order to make sure there was no obvious regression. >> >> >> >> I'm wildly cross-posting this patch series, including to lists I'm not >> >> subscribed to. Please keep me on Cc for any comment you may have. >> >> >> >> The code is also available at: >> >> git://git.kernel.org/pub/scm/linux/kernel/git/maz/u-boot.git wip/psci >> >> >> >> Cheers, >> >> >> >> M. >> > >> > Marc, I'm unclear what you want to do with this series. You mention >> > that its first 10 patches will apply to U-Boot, but I am not sure >> > whether you are just indicating that it is possible to apply them or >> > asking for these 10 patches to go in U-Boot mainline. Or is it >> > something else yet? >> >> Well, I rarely write code just for the sake of forking a critical >> project ;-) >> >> So let's be 100% explicit: Yes, I'm hereby asking for these patches to >> be merged. They offer a service that is required by the Linux kernel as >> well as Xen. They are in active use on the Allwinner sun7i platform as >> well as Versatile Express (though the later doesn't have a PSCI >> implementation). >> >> Now, given that two months have gone past without much comment other >> than the odd "hey, works great", I don't really know where to take that. >> >> Are you willing to review the patches? > > Well, I rarely ask about patches just for the sake of conversation. O:-) > > So yes, I am willing to review them -- and I suspect others are, as > well. Nobody commented the V3 series on the U-Boot list -- save for > Jon's comment about the series needing a rebase -- which could mean no > one here is unhappy with them... or they were discussed and possibly > acted upon on linux-sunxi, where the replies were redirected. I don't > follow linux-sunx closely, so I couldn't tell. :) No, so far there hasn't been much discussion, and people seem happy with it. I have a couple of fixes lined up, but nothing major. Also, a number of the patches are actually fixes that should really make it into the U-Boot tree, no matter if the PSCI code is merged or not. Some of them make the kernel go completely bonkers, other introduce the risk of U-Boot falling over in style. > Still, I am trying to figure out the whole Allwinner nebula and see how > things are supposed to work out between their various SoCs and make > sure to avoid duplicate/incompatible effort (you're mentioning the A20, > there seems to be A31 work underway too elsewhere). I am starting to > wonder whether an ARM allwinner sub-repo might make sense. Tom, > Wolfgang? Ian Campbell (cc-ed) is actively pushing out patches to support the A20 in mainline U-Boot (I believe you've been on the receiving end of these), and I plan to rebase my series on top of his. Still, the A20 support is only a small part of the code, used as an example of how to implement PSCI on a rather simple platform. This can easily be split out and merged via different trees. Thanks, M. -- Jazz is not dead. It just smells funny.