[U-Boot] [PATCH 0/4] AE350 support SMP boot from flash

[Auer, Lukas]

Hi Rick,

On Wed, 2019-04-24 at 09:35 +0800, Rick Chen wrote:
> Hi Lukas
> 
> Auer, Lukas <lukas.auer at aisec.fraunhofer.de> 於 2019年4月24日 週三 上午3:58寫道：
> > Hi Rick,
> > 
> > On Tue, 2019-04-23 at 13:42 +0800, Andes wrote:
> > > From: Rick Chen <rick at andestech.com>
> > > 
> > > In current RISC-V SMP flow, AE350 will encounter the the write
> > > failure problem since hart_lottery and available_harts_lock was
> > > not in ram address but in flash address when booing from flash.
> > > 
> > > This patch can help to fix the failure problem when AE350 was
> > > booting from flash by disable this two features.
> > > 
> > 
> > Can you describe the issue you are seeing a bit more. The write
> > failures are both to variables in the .data section, which should be
> > writable. Perhaps the write failures can be avoided by moving the .data
> > section or just the variable to RAM?
> > 
> 
> When I compile AE350's CONFIG_SYS_TEXT_BASE=0x80000000 which is spi flash base.
> And burn u-boot.bin into AE350 spi flash. Power off / on, U-Boot will
> run in XIP mode.
> At this time prior_stage_fdt_address will be in flash address(0x8004e9e8)
> So it is not writable.
> 
> 80000042:       16021563                bnez    tp,800001ac
> <secondary_hart_loop>
> 80000046:       0004f297                auipc   t0,0x4f
> 8000004a:       9a22a283                lw      t0,-1630(t0) #
> 8004e9e8 <prior_stage_fdt_address+0x3f74>
> 8000004e:       0092a023                sw      s1,0(t0)
> 

Ok, that makes sense.
Another option would be to move the variable to RAM or some other
location, which is write-accessible when U-Boot starts. Would this
work?
I think it would be good to support the hart lottery and the available
harts mask in all configurations.

Thanks,
Lukas