[vbox-dev] PATCH: Implement support for multiple custom ACPI tables

Michal Necasek michal.necasek at oracle.com
Tue Sep 4 14:44:37 UTC 2018


  Thanks for the patch! I quickly looked over it and it looks to me that 
the behavior of existing VMs with the 
VBoxInternal/Devices/acpi/0/Config/CustomTable keys set will subtly 
change because the call to

acpiR3PrepareHeader(pThis, &cust.header, "CUST", sizeof(cust), 1);

is no longer done and the incoming data is copied a bit differently. Can 
you explain why that's not done or why it can't cause any problems?

  Wouldn't it be better to keep the existing behavior for CustomTable 
and just add CustomTable1/2/3 with slightly different behavior?

  Also, do you have a concrete example of ACPI tables that one might 
want to pass to a VM this way?


On 8/24/2018 9:14 PM, Canardos . wrote:
> Hi Devs,
> This patch expands on work done several years ago, extending support for 
> custom ACPI tables from a single table to four tables, and potentially N 
> tables in future.
> The changes assist malware researchers to better emulate a physical 
> machine (although increasing the aggregate allowable table size will 
> assist further) as well as those with valid OEM licenses having issues 
> property passing through both SLIC and license tables.
> I limited the implementation to four custom tables given current VBox 
> limitations on the aggregate size of ACPI tables, but the code changes 
> support N tables.
> The new configuration keys are "CustomTable0..3". Legacy behavior has 
> been maintained, with any existing config entries for "CustomTable", or 
> "SLICTable" being used in the absence of a "CustomTable0" entry.
> The changes have been tested on Debian 9.5 (kernel 4.9.0-7/amd64) and 
> Manjaro (kernel 4.14.65-1/amd64) hosts with 32 and 64-bit Linux guests.
> I've endeavored to reflect the code style of the file I was working in, 
> please let me know if anything is amiss.
> All attached code is released under the MIT License.
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