Acidanthera UEFI Development Kit based on EDK II edk2-stable202311
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Michael Kubacki aab3b9b9a1 MdeModulePkg/Variable: Add RT GetVariable() cache support
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2220

This change reduces SMIs for GetVariable () by maintaining a
UEFI variable cache in Runtime DXE in addition to the pre-
existing cache in SMRAM. When the Runtime Service GetVariable()
is invoked, a Runtime DXE cache is used instead of triggering an
SMI to VariableSmm. This can improve overall system performance
by servicing variable read requests without rendezvousing all
cores into SMM.

The runtime cache  can be disabled with by setting the FeaturePCD
gEfiMdeModulePkgTokenSpaceGuid.PcdEnableVariableRuntimeCache
to FALSE. If the PCD is set to FALSE, the runtime cache will not be
used and an SMI will be triggered for Runtime Service
GetVariable () and GetNextVariableName () invocations.

The following are important points regarding the behavior of the
variable drivers when the variable runtime cache is enabled.

1. All of the non-volatile storage contents are loaded into the
   cache upon driver load. This one time load operation from storage
   is preferred as opposed to building the cache on demand. An on-
   demand cache would require a fallback SMI to load data into the
   cache as variables are requested.

2. SetVariable () requests will continue to always trigger an SMI.
   This occurs regardless of whether the variable is volatile or
   non-volatile.

3. Both volatile and non-volatile variables are cached in a runtime
   buffer. As is the case in the current EDK II variable driver, they
   continue to be cached in separate buffers.

4. The cache in Runtime DXE and SMM are intended to be exact copies
   of one another. All SMM variable accesses only return data from the
   SMM cache. The runtime caches are only updated after the variable I/O
   operation is successful in SMM. The runtime caches are only updated
   from SMM.

5. Synchronization mechanisms are in place to ensure the runtime cache
   content integrity with the SMM cache. These may result in updates to
   runtime cache that are the same in content but different in offset and
   size from updates to the SMM cache.

When using SMM variables with runtime cache enabled, two caches will now
be present.
1. "Runtime Cache" - Maintained in VariableSmmRuntimeDxe. Used to service
   Runtime Services GetVariable () and GetNextVariableName () callers.
2. "SMM Cache" - Maintained in VariableSmm to service SMM GetVariable ()
   and GetNextVariableName () callers.
   a. This cache is retained so SMM modules do not operate on data outside
      SMRAM.

Because a race condition can occur if an SMI occurs during the execution
of runtime code reading from the runtime cache, a runtime cache read lock
is introduced that explicitly moves pending updates from SMM to the runtime
cache if an SMM update occurs while the runtime cache is locked. Note that
it is not expected a Runtime services call will interrupt SMM processing
since all CPU cores rendezvous in SMM.

It is possible to view UEFI variable read and write statistics by setting
the gEfiMdeModulePkgTokenSpaceGuid.PcdVariableCollectStatistics FeaturePcd
to TRUE and using the VariableInfo UEFI application in MdeModulePkg to dump
variable statistics to the console. By doing so, a user can view the number
of GetVariable () hits from the Runtime DXE variable driver (Runtime Cache
hits) and the SMM variable driver (SMM Cache hits). SMM Cache hits for
GetVariable () will occur when SMM modules invoke GetVariable ().

Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
2019-11-05 21:55:54 -08:00
ArmPkg ArmPkg: strip trailing whitespace 2019-10-04 11:18:22 +01:00
ArmPlatformPkg ArmPlatformPkg: strip trailing whitespace 2019-10-04 11:18:22 +01:00
ArmVirtPkg ArmVirtPkg/PlatformBootManagerLib: Don't update progress if Pcd is 0 2019-10-16 18:27:42 +02:00
BaseTools BaseTools GenFw: Fix the issue to update the wrong size as SectionSize 2019-10-24 09:41:31 +08:00
Conf BaseTools:Delete FrameworkDatabase from BaseTools/Conf 2019-05-09 15:03:30 +08:00
CryptoPkg CryptoPkg: Upgrade OpenSSL to 1.1.1d 2019-11-05 10:42:07 +08:00
DynamicTablesPkg DynamicTablesPkg: Arm SRAT Table Generator 2019-10-21 16:16:50 +01:00
EmbeddedPkg EmbeddedPkg/Universal/MmcDxe: "fix" CloseProtocol() call in BindingStop() 2019-10-09 09:40:09 +02:00
EmulatorPkg EmulatorPkg: Enable CLANG9 tool chain 2019-10-24 09:41:34 +08:00
FatPkg FatPkg: Fix spelling errors 2019-10-22 17:24:34 -07:00
FmpDevicePkg FmpDevicePkg: Fix spelling errors 2019-10-23 08:08:08 -07:00
IntelFsp2Pkg IntelFsp2Pkg/SplitFspBin.py: Command crashed when FV almost full. 2019-10-28 10:28:56 +08:00
IntelFsp2WrapperPkg IntelFsp2WrapperPkg: Remove unneeded MdeModulePkg dependency 2019-09-05 02:10:03 +08:00
MdeModulePkg MdeModulePkg/Variable: Add RT GetVariable() cache support 2019-11-05 21:55:54 -08:00
MdePkg MdePkg-UefiSpec.h: Add UEFI 2.8 new memory attributes 2019-11-04 08:53:53 +08:00
NetworkPkg NetworkPkg/HttpDxe: Set the HostName for the verification (CVE-2019-14553) 2019-11-02 12:08:25 +01:00
OvmfPkg OvmfPkg: Enable CLANG9 tool chain 2019-10-24 09:41:35 +08:00
PcAtChipsetPkg PcAtChipsetPkg: Fix spelling errors 2019-10-22 17:28:09 -07:00
SecurityPkg SecurityPkg: Fix spelling errors 2019-10-23 10:23:23 -07:00
ShellPkg ShellPkg/Shell/FileHandleWrappers.c: Add check for MemFile->Buffer 2019-11-06 13:26:21 +08:00
SignedCapsulePkg SignedCapsulePkg: fix AARCH64 build 2019-10-18 12:56:09 +01:00
SourceLevelDebugPkg SourceLevelDebugPkg DebugCommLibUsb3: Address NULL ptr dereference case 2019-08-12 09:46:47 +08:00
StandaloneMmPkg StandaloneMmPkg/Core: Fix typo in function name 2019-10-17 09:09:25 +08:00
UefiCpuPkg UefiCpuPkg/MpInitLib: Remove global variable X2ApicEnable 2019-11-05 10:03:44 +08:00
UefiPayloadPkg UefiPayloadPkg/BlSupportDxe: fix ReserveResourceInGcd() calls 2019-10-09 09:40:10 +02:00
.gitignore edk2: Add .DS_Store to .gitignore for macOS 2017-05-19 15:14:34 -07:00
.gitmodules ArmPkg: import Berkeley Softfloat library as git submodule 2019-05-31 17:53:44 +02:00
License-History.txt edk2: Add License-History.txt 2019-04-09 09:10:18 -07:00
License.txt edk2: Change License.txt from 2-Clause BSD to BSD+Patent 2019-04-09 09:10:18 -07:00
Maintainers.txt Maintainers.txt: Update my e-mail address 2019-10-29 02:12:31 +01:00
Readme.md Readme.md: add submodule policy and clone commands 2019-08-15 09:56:37 +08:00
edksetup.bat Add VS2019 Support on ToolSetup Batches 2019-09-23 22:42:41 +08:00
edksetup.sh edksetup.sh: remove redundant -?, -h and --help in options parsing 2019-07-23 10:41:55 +02:00

Readme.md

EDK II Project

A modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications from www.uefi.org.

The majority of the content in the EDK II open source project uses a BSD-2-Clause Plus Patent License. The EDK II open source project contains the following components that are covered by additional licenses:

The EDK II Project is composed of packages. The maintainers for each package are listed in Maintainers.txt.

Resources

Code Contributions

To make a contribution to a TianoCore project, follow these steps.

  1. Create a change description in the format specified below to use in the source control commit log.

  2. Your commit message must include your Signed-off-by signature

  3. Submit your code to the TianoCore project using the process that the project documents on its web page. If the process is not documented, then submit the code on development email list for the project.

  4. It is preferred that contributions are submitted using the same copyright license as the base project. When that is not possible, then contributions using the following licenses can be accepted:

    For documentation:

    Contributions of code put into the public domain can also be accepted.

    Contributions using other licenses might be accepted, but further review will be required.

Developer Certificate of Origin

Your change description should use the standard format for a commit message, and must include your Signed-off-by signature.

In order to keep track of who did what, all patches contributed must include a statement that to the best of the contributor's knowledge they have the right to contribute it under the specified license.

The test for this is as specified in the Developer's Certificate of Origin (DCO) 1.1. The contributor certifies compliance by adding a line saying

Signed-off-by: Developer Name developer@example.org

where Developer Name is the contributor's real name, and the email address is one the developer is reachable through at the time of contributing.

Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

Sample Change Description / Commit Message

From: Contributor Name <contributor@example.com>
Subject: [Repository/Branch PATCH] Pkg-Module: Brief-single-line-summary

Full-commit-message

Signed-off-by: Contributor Name <contributor@example.com>

Notes for sample patch email

  • The first line of commit message is taken from the email's subject line following [Repository/Branch PATCH]. The remaining portion of the commit message is the email's content.
  • git format-patch is one way to create this format

Definitions for sample patch email

  • Repository is the identifier of the repository the patch applies. This identifier should only be provided for repositories other than edk2. For example edk2-BuildSpecification or staging.
  • Branch is the identifier of the branch the patch applies. This identifier should only be provided for branches other than edk2/master. For example edk2/UDK2015, edk2-BuildSpecification/release/1.27, or staging/edk2-test.
  • Module is a short identifier for the affected code or documentation. For example MdePkg, MdeModulePkg/UsbBusDxe, Introduction, or EDK II INF File Format.
  • Brief-single-line-summary is a short summary of the change.
  • The entire first line should be less than ~70 characters.
  • Full-commit-message a verbose multiple line comment describing the change. Each line should be less than ~70 characters.
  • Signed-off-by is the contributor's signature identifying them by their real/legal name and their email address.

Submodules

Submodule in EDK II is allowed but submodule chain should be avoided as possible as we can. Currently EDK II contains two submodules

  • CryptoPkg/Library/OpensslLib/openssl
  • ArmPkg/Library/ArmSoftFloatLib/berkeley-softfloat-3

The latter one is actually required by previous one. It's inevitable in openssl-1.1.1 (since stable201905) for floating point parameter conversion, but should be dropped once there's no such need in future release of openssl.

To get a full, buildable EDK II repository, use following steps of git command

$ git clone https://github.com/tianocore/edk2.git
$ cd edk2
$ git submodule update --init
$ cd ..

If there's update for submodules, use following git commands to get the latest submodules code.

$ cd edk2
$ git pull
$ git submodule update

Note: When cloning submodule repos, '--recursive' option is not recommended. EDK II itself will not use any code/feature from submodules in above submodules. So using '--recursive' adds a dependency on being able to reach servers we do not actually want any code from, as well as needlessly downloading code we will not use.