[U-Boot] [PATCH v2] arm: socfpga: do not reboot via SRAM

[Marek Vasut]

On 7/10/19 9:06 PM, Simon Goldschmidt wrote:
> This removes the code that enables the Boot ROM to just jump to SRAM
> instead of loading SPL from the original boot source on warm reboot.
> 
> The reason for removing this is that it is insecure: SRAM might be
> overwritten at the time the warm reboot is done. Instead, use the default
> behaviour of loading SPL from the configured boot source medium.
> 
> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
> ---
> 
> Changes in v2:
> - remove the compatibility code restoring the old "reboot from SRAM"
>   behaviour via an env var callback as it turned out such a hack should
>   not be included by default
> - (v1 patch subject was: "arm: socfpga: control reboot from SRAM via env
>   callback")
> 
>  arch/arm/mach-socfpga/misc_gen5.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/arch/arm/mach-socfpga/misc_gen5.c b/arch/arm/mach-socfpga/misc_gen5.c
> index 71547d81ab..38bff8a450 100644
> --- a/arch/arm/mach-socfpga/misc_gen5.c
> +++ b/arch/arm/mach-socfpga/misc_gen5.c
> @@ -6,6 +6,7 @@
>  #include <common.h>
>  #include <asm/io.h>
>  #include <errno.h>
> +#include <environment.h>
>  #include <fdtdec.h>
>  #include <linux/libfdt.h>
>  #include <altera.h>
> @@ -182,15 +183,6 @@ int arch_early_init_r(void)
>  {
>  	int i;
>  
> -	/*
> -	 * Write magic value into magic register to unlock support for
> -	 * issuing warm reset. The ancient kernel code expects this
> -	 * value to be written into the register by the bootloader, so
> -	 * to support that old code, we write it here instead of in the
> -	 * reset_cpu() function just before resetting the CPU.
> -	 */
> -	writel(0xae9efebc, &sysmgr_regs->romcodegrp_warmramgrp_enable);

Does this break ancient altera kernel versions ? Do we care ?