Hi Marc, On Wed, 16 Apr 2014 17:09:07 +0100, Marc Zyngier <marc.zyng...@arm.com> wrote:
> On 16/04/14 15:45, Albert ARIBAUD wrote: > > Hi Marc, > > > > On Sat, 15 Feb 2014 13:36:24 +0000, Marc Zyngier > > <marc.zyngier-5wv7dgni...@public.gmane.org> 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. :) 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? > Thanks, > > M. Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
