Re: [PATCH v5 09/19] arch_topology: Use the last level cache information from the cacheinfo

[Conor.Dooley]

On 29/06/2022 19:47, Sudeep Holla wrote:
> On Wed, Jun 29, 2022 at 06:18:25PM +0000, Conor.Dooley@xxxxxxxxxxxxx wrote:
>> On 29/06/2022 18:49, Conor.Dooley@xxxxxxxxxxxxx wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> On 27/06/2022 17:50, Sudeep Holla wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>
>>>> The cacheinfo is now initialised early along with the CPU topology
>>>> initialisation. Instead of relying on the LLC ID information parsed
>>>> separately only with ACPI PPTT elsewhere, migrate to use the similar
>>>> information from the cacheinfo.
>>>>
>>>> This is generic for both DT and ACPI systems. The ACPI LLC ID information
>>>> parsed separately can now be removed from arch specific code.
>>>
>>> Hey Sudeep,
>>> I bisected broken boot on PolarFire SoC to this patch in next-20220629 :/
>>> I suspect the issue is a missing "next-level-cache" in the the dt:
>>> arch/riscv/boot/dts/microchip/mpfs.dtsi
> 
> Good that I included this in -next, I had not received any feedback from
> RISC-V even after 5 iterations.

I'll be honest, I saw the titles and CC list and made some incorrect
assumptions as to whether looking at it was worthwhile! I am not at
this all too long and what is/isn't important to look at often is not
obvious to me. But hey, our CI boots -next every day for a reason ;)

> I also see this DTS is very odd. It also
> states CPU0 doesn't have L1-D$ while the other 4 CPUs have L1-D$. Is that
> a mistake or is it the reality ?

AFAIK, reality. It's the same for the SiFive fu540 (with which this shares
a core complex. See page 12:
https://static.dev.sifive.com/FU540-C000-v1.0.pdf

> Another breakage in userspace cacheinfo
> sysfs entry of cpu0 has both I$ and D$.

Could you clarify what this means please?
Thanks,
Conor.