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

[Tom Rini]

On Fri, Nov 03, 2023 at 12:14:46PM -0600, Simon Glass wrote:
> 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 SMBIOS 2 is only a fallback for outdated tools.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.

We also don't have the use case for when EFI is not used defined and
understood, so it can wait until then?

-- 
Tom
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