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? Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
