[U-Boot] [PATCH v3 00/13] ARMv7: add PSCI support to u-boot

[Albert ARIBAUD]

Hi Marc,

On Sat, 15 Feb 2014 13:36:24 +0000, Marc Zyngier
<marc.zyngier-5wv7dgnIgG8 at 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.