[PATCH 1/1] sandbox: ensure that state->ram_buf is in low memory

Heinrich Schuchardt xypron.glpk at gmx.de
Thu May 13 16:53:12 CEST 2021

On 5/13/21 4:36 PM, Simon Glass wrote:
> Hi Heinrich,
> On Wed, 12 May 2021 at 15:28, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>> Am 12. Mai 2021 18:01:17 MESZ schrieb Simon Glass <sjg at chromium.org>:
>>> Hi Heinrich,
>>> On Tue, 11 May 2021 at 13:03, Heinrich Schuchardt <xypron.glpk at gmx.de>
>>> wrote:
>>>> Addresses in state->ram_buf must be in the low 4 GiB of the address
>>> space.
>>>> Otherwise we cannot correctly fill SMBIOS tables. This shows up in
>>> warnings
>>>> like:
>>>>      WARNING: SMBIOS table_address overflow 7f752735e020
>>> This sounds like a bug in the smbios-table code. For sandbox it should
>>> perhaps use addresses instead of pointers.
>>> I think that code (that I unfortunately wrote) was an expeditious way
>>> of getting it running, but is not correct.
>> The field you are filling is only 32bit wide. I wonder how that table is meant to work on systems where the lowest memory address is above 4 GiB. Such ARMv8 systems exist.
> map_to_sysmem() will give you a 32-bit wide address. Yes SMBIOS is
> legacy and designed for 4GB.

I know map_to_sysmem(). But you wrote in lib/smbios.c:487:

  * We must use a pointer here so things work correctly on sandbox. The
  * user of this table is not aware of the mapping of addresses to
  * sandbox's DRAM buffer.

For testing you could start a binary with command 'bootefi' or 'booti'
and that binary would analyze the table. So yes, your comment holds true
and you must not use map_to_sysmem() here.

Best regards


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