diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-02-18 09:59:09 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-02-18 12:00:10 +0100 |
| commit | ca6d61b22658e6d13b4a73589f5e5df0b0e7ba03 (patch) | |
| tree | b0cc40c73596e1af21d18c01616bc18c151d6033 /ArmVirtPkg | |
| parent | 9eec4d38c027e9eb95c545875a1f847f0cb3dcbf (diff) | |
| download | edk2-platforms-ca6d61b22658e6d13b4a73589f5e5df0b0e7ba03.tar.xz | |
ArmVirtPkg: ArmVirtQemu: expose only 64-bit entry point for v3.0+ SMBIOS
The legacy 32-bit SMBIOS entry point has little use on AARCH64 systems,
since many such systems have no 32-bit addressable physical RAM, and so
OSes that implement SMBIOS will have to be able to deal with the 64-bit
entry point anyway.
Given that the OS will map main memory in 1 GB chunks if it can, and that
punching a page sized hole (e.g., for SMBIOS data) into it will result in
the whole 1 GB chunk being mapped using 2 MB and 4 KB blocks instead, it
is important to group memory reservations from the OS as much as we can,
and allocating below 4 GB for no good reason interferes with that.
This is especially important under virtualization, considering that each
*level* of lookup at stage 1 (the guest virtual page table) will result in
a full page table walk at stage 2 (the guest PA to host PA mapping).
So expose only the 64-bit entry point when the SMBIOS tables adhere to
version 3.0 or later.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Diffstat (limited to 'ArmVirtPkg')
| -rw-r--r-- | ArmVirtPkg/ArmVirtQemu.dsc | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc index e6440ec5da..e2641fd2c2 100644 --- a/ArmVirtPkg/ArmVirtQemu.dsc +++ b/ArmVirtPkg/ArmVirtQemu.dsc @@ -169,6 +169,14 @@ # support anything bigger, even if the host hardware does
gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize|40
+ # Clearing BIT0 in this PCD prevents installing a 32-bit SMBIOS entry point,
+ # if the entry point version is >= 3.0. AARCH64 OSes cannot assume the
+ # presence of the 32-bit entry point anyway (because many AARCH64 systems
+ # don't have 32-bit addressable physical RAM), and the additional allocations
+ # below 4 GB needlessly fragment the memory map. So expose the 64-bit entry
+ # point only, for entry point versions >= 3.0.
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSmbiosEntryPointProvideMethod|0x2
+
[PcdsDynamicDefault.common]
## If TRUE, OvmfPkg/AcpiPlatformDxe will not wait for PCI
# enumeration to complete before installing ACPI tables.
|