[PATCH v2] smbios: arm64: Allow table to be written at a fixed addr

[Simon Glass]

Hi Heinrich,

On Fri, 3 Nov 2023 at 11:52, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
>
>
> Am 3. November 2023 19:12:40 OEZ schrieb Simon Glass <sjg at chromium.org>:
> >Hi,
> >
> >On Sat, 28 Oct 2023 at 12:41, Simon Glass <sjg at chromium.org> wrote:
> >>
> >> [unfortunately I am not receiving email from the list at present]
> >>
> >> Hi Heinrich,
> >>
> >> On Wed, 25 Oct 2023 at 21:39, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >> >
> >> > On 10/25/23 04:49, Simon Glass wrote:
> >> > > Hi Heinrich,
> >> > >
> >> > > On Tue, 24 Oct 2023 at 18:22, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >> > >>
> >> > >>
> >> > >>
> >> > >> Am 25. Oktober 2023 01:31:19 MESZ schrieb Simon Glass <sjg at chromium.org>:
> >> > >>> U-Boot typically sets up its malloc() pool near the top of memory. On
> >> > >>> ARM64 systems this can result in an SMBIOS table above 4GB which is
> >> > >>> not supported by SMBIOSv2.
> >> > >>>
> >> > >>> Work around this problem by providing a new option to choose an address
> >> > >>> below 4GB (but as high as possible), if needed.
> >> > >>
> >> > >> You must not overwrite memory controlled by the EFI subsystem without calling its allocator.  We should provide SMBIOS 3. SMBIOS 2 is only a fallback for outdated tools.
> >> > >
> >> > > That is not my intention and I don't believe this code does that. EFI
> >> > > is not running at this point, is it?
> >> >
> >> > The function install_smbios_table() only exists if CONFIG_EFI_LOADER=y.
> >>
> >> That is because ARM devices don't normally need it, right? Anyway,
> >> that option isn't related to this patch. If ARM devices started using
> >> SMBIOS and had another way to pass it to Linux (other than EFI) then
> >> we would want to install it.
> >>
> >> >
> >> > We have:
> >> > EVENT_SPY_SIMPLE(EVT_LAST_STAGE_INIT, install_smbios_table);
> >> > This is invoked after efi_memory_init().
> >> >
> >> > The EFI specification requires that the memory area occupied by the
> >> > SMBIOS table uses one of a specific set of memory types where
> >> > EfiRuntimeServicesData is recommended. So you must call
> >> >
> >> > u64 addr = UINT_MAX;
> >> > ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
> >> > EFI_RUNTIME_SERVICES_DATA, efi_size_in_pages(size), *addr);
> >> >
> >> > to allocate the memory. If the return code is not EFI_SUCCESS, no memory
> >> > below 4 GiB is available.
> >>
> >> The root problem here is that x86 and ARM used to work differently.
> >> When the ARM SMBIOS stuff was done, it worked by writing the SMBIOS
> >> table as part of the 'bootefi' command. On x86, the tables were
> >> written on startup, so you can examine them within U-Boot. Clearly the
> >> x86 approach is correct. For one thing, a previous-stage bootloader
> >> may set up the tables, so it simply isn't valid to write them in that
> >> case. So we need to separate writing the tables from telling EFI about
> >> them.
> >>
> >> So I have fixed that, so ARM now writes the tables at the start. But
> >> using an EFI allocation function is clearly not right. This is generic
> >> code, nothing to do with EFI, really. In fact, the SMBIOS writing
> >> should move out of efi_loader. The install_smbios_table() function
> >> should be somewhere in lib, i suppose, with just efi_smbios_register()
> >> sitting in lib/efi_loader
> >>
> >> Also, why is efi_memory_init() called early in init? Is there anything
> >> that needs that in the init sequence? Could we move it to the end, or
> >> perhaps skip it completely until the 'bootefi' command is used?
> >>
> >> Another point I should make is that it should be fine for U-Boot to
> >> put something in memory and then call efi_add_memory_map() to tell EFI
> >> about it. What problems does that cause? It isn't as if EFI allocates
> >> things in the 'conventional' memory (is that the name for memory below
> >> 4GB?) This is how efi_acpi_register() works.
> >>
> >> (Aside: it is bizarre to me that CONFIG_EFI_LOADER appears in
> >> drivers/video/rockchip_rk_vop.c and other such files)
> >>
> >> >
> >> > >
> >> > > The bit I am confused about is that we don't support SMBIOS3 in
> >> > > U-Boot. I am trying to fix an introduced bug...
> >> >
> >> > I would not know why we should not use SMBIOS 3.
> >>
> >> Neither do I. Perhaps there are compatibility concerns? If it is OK to
> >> do that then we could go back to my previous series [1]. What do you
> >> think?
> >
> >Tom responded but I missed it. In part it says:
> >
> >"So, can we please start by just doing the minimal changes to get the
> >SMBIOS table done correctly for memory above 4G, via EFI, and then start
> >the next steps?"
> >
> >I am OK to do an EFI hack for ARM so long as we agree that after the
> >release we will revert it and generate the table using generic memory
> >allocation, not dependent on EFI. Does that sound reasonable?
> >
> >I don't seem to have received any response from Heinrich to the
> >various points I made above. I cannot see any response on patchwork
> >either.
> >
> >Regards,
> >Simon
>
> All memory below the stack is controlled by the EFI subsystem. I notified you of the function you need to call. I can't see what information you are lacking.

That is fine when EFI is used, but what about when it is not? That is
the piece I don't yet understand.

Regards,
Simon