phosphor-isolation

[Andrew Jeffery]

On Fri, 20 Sep 2019, at 03:03, James Feist wrote:
> I enabled phosphor-isolation on my system and noticed that kcs no longer 
> worked afterwards. Commenting out this section:
> 
> https://github.com/openbmc/meta-phosphor/blob/a1cee09419cb1467c3d2b7bf996b40089f0d06f4/aspeed-layer/recipes-bsp/u-boot/files/0001-aspeed-Disable-unnecessary-features.patch#L230
> 
> +	/* iLPC2AHB */
> +	val = readl(AST_SCU_BASE + AST_SCU_HW_STRAP1);
> +	val |= SCU_HW_STRAP_LPC_DEC_SUPER_IO;
> +	writel(val, AST_SCU_BASE + AST_SCU_HW_STRAP1);
> 
> 
> Seems to make KCS work again. 

That is an unexpected result. Have you asked ASPEED about it? I've added
Ryan to Cc. I must admit I didn't test the patch with systems that use KCS
because OpenPOWER exclusively uses BT for IPMI (though we're starting
to exploit the KCS interfaces for an LPC MCTP binding).

Having said that, the systems that we're testing our LPC MCTP binding on
would have this patch applied, so presumably we're not seeing the same
effect there. They're 2500-based systems, is that what you're testing with?

> Do we need this part set? If so, should we 
> create a phosphor-isolation-kcs and phosphor-isolation-bt?

I hope not, given that leaving the SuperIO decoding enable allows the
host to (slowly) scrape BMC memory (or if iLPC2AHB writes are allowed,
open faster backdoors). We should root-cause the issue before exploring
this path.

Andrew