[SeaBIOS] [PATCH 2/2] accept MADT over fw_cfg

Kevin O'Connor kevin at koconnor.net
Thu Mar 21 01:22:30 CET 2013

On Wed, Mar 20, 2013 at 10:53:05PM +0100, Laszlo Ersek wrote:
> Signed-off-by: Laszlo Ersek <lersek at redhat.com>

I think we need to figure out what the final fw_cfg interface for
ACPI, SMBIOS, mptable, and PIR will be.

We can use the current fw_cfg ACPI table passing mechanism for ACPI,
but there are a couple of things that need to be worked out.  For each
table, there must be a way to determine if SeaBIOS should build it, or
if the table should not be present at all.  For example, if MADT isn't
present in the fw_cfg, is that because SeaBIOS is expected to build it
or because it is not expected to be present at all?  This also needs
to be resolved for SSDT tables, which can have zero, one, or more
instances.  Finally, the mechanism should define how the RSDP
signatures is set as well as support both RSDT and XSDT tables (with
signatures defined by QEMU for these as well).

For SMBIOS, I don't think we should use the existing fw_cfg mechanism.
It's too complicated for what is needed.  Instead, one fw_cfg "file"
entry with the whole smbios table should suffice.  For mptable and
PIR, there is no current mechanism, so we can add new fw_cfg "files"
for them.  However, for all of these SeaBIOS needs to be able to
determine when it needs to create the table and when no table should
be published at all.

One possible way to accomplish the above would be to add an
"all_tables_from_qemu" fw_cfg entry that turned off all of the
existing SeaBIOS code.  There are probably other ways.



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