Re: [PATCH] target/arm: build smbios 19 table

[Peter Maydell <peter.maydell@linaro.org>]

On Sun, 20 Nov 2022 at 17:53, Mihai Carabas <mihai.carabas@oracle.com> wrote:
>
> La 18.11.2022 21:11, Peter Maydell a scris:
> > On Fri, 18 Nov 2022 at 17:37, Mihai Carabas <mihai.carabas@oracle.com> wrote:
> >> Use the base_memmap to build the SMBIOS 19 table which provides the address
> >> mapping for a Physical Memory Array (from spec [1] chapter 7.20).
> >>
> >> This was present on i386 from commit c97294ec1b9e36887e119589d456557d72ab37b5
> >> ("SMBIOS: Build aggregate smbios tables and entry point").
> >>
> >> [1] https://urldefense.com/v3/__https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.5.0.pdf__;!!ACWV5N9M2RV99hQ!KF2xmQw9nxPvqvNCgDleyVHv4MoZseoZFHmR1veww7O2BmRxSH1spOCNWX-c-FvzcaR_o8PunXSWWH2ECvFqlR4E7vw$
> >>
> >> Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
> > Is this a bug fix, or a new feature? What are the consequences
> > of it being missing? Is this important enough to go into the 7.2
> > release? (My default position would be "no", given this has been
> > like this on the virt board for a very long time.)
>
>
> This is required by ARM SystemReady Virtual Environment [1]. As
> described in the Arm SystemReady Requirements Specification v2.0
>   [2] page 9, 2.5.1 SystemReady Virtual Environment (VE) v1.0
> requirements,: "FirmwareTestSuite (FWTS) must still be used" -> fwts
> checks for the presence of SMBIOS type 19 table and fails the test in
> this case.

OK, so it's a spec requirement. Are there any actual realworld
guests that don't work because we get this wrong ?

> > Do we need to care here about pluggable memory devices?
> > (We seem to do something with them in the ACPI tables
> > via build_srat_memory(), so maybe not?)

> Here you are refering to the fact that when we hot plug a memory dim, to
> automatically update smbios type 19 entry/entries?

I don't know anything at all really about any of these ACPI/SMBIOS/etc
data structures. I do know that the virt board has two ways to
have RAM in it:
 * the 'standard RAM" that you get with -m 1024M etc
 * the pluggable DIMMs

So I'm just asking if this bit of code needs to account for
the second kind, or if this SMBIOS table type only cares about
the first kind. If you don't know the answer then we can
check with the person who added the pluggable DIMM support.

thanks
-- PMM