Tianocore/edk2.git/PcAtChipsetPkg, branch master

PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe: Avoid torn RTC time reads

2026-08-25T20:10:25+00:00

GetTime()/GetWakeupTime() wait for the RTC Update-In-Progress (UIP) bit to clear, then read the time/date registers (offsets 0-9) back to back. A clear UIP bit only guarantees a documented minimum before the next update cycle begins, not that the whole read fits inside it. Where a single RTC access is slow the read overruns that window and picks up undefined data from registers the update cycle has disconnected from the bus; the corrupted field fails the range check and GetTime() returns EFI_DEVICE_ERROR, which intermittently fails OS boot and resume. Read the registers through RtcReadTimeDateOrFail(), which samples the Seconds register before the read and requires both UIP still clear and Seconds unchanged afterwards. The update cycle is specified to increment the stored time, so Seconds changes if and only if an update occurred, which detects a collision anywhere inside the read. RtcReadRegistersSafe() drives that with at most one retry and copies out only on success. The full reasoning, including why one retry is enough, is documented at those two functions. The four read paths (GetTime, Init, GetWakeupTime, SetWakeupTime disable-alarm) use the helper; write paths already inhibit updates via the Register B SET bit and are unchanged. The helper enters its own update-free window, so the up-front RtcWaitToUpdate() in PcRtcGetTime() and in the PcRtcInit() read path is now redundant and is removed. Signed-off-by: James Lu

PcAtChipsetPkg: Add VarPolicy to PcAtRealTimeClock variables

2026-07-31T07:14:46+00:00

Register a variable policy for L"RTCALARM" and L"RTC". The policy will enforce strict requiremnts for the variable size and attributes, and will block updates to the variables unless those requirements are met. Signed-off-by: Aaron Pop

PcAtChipsetPkg/SerialIoLib: Allow configurable UART IO Port Base Address

2026-07-31T02:55:23+00:00

Today's implementation used a hardcoded value for the I/O Port Base Address. This creates a problem for platform configurability. If a platform needs to use a different I/O port address, then it requires modification of a source file. Create gPcAtChipsetPkgTokenSpaceGuid.PcdUartIoPortBaseAddress as a FixedAtBuild pcd scoped to PcAtChipsetPkg, with default value for 0x3f8 to match existing value, and update code to use PCD. Signed-off-by: Aaron Pop

Global: Set MarkdownLintCheck plugin to AuditOnly

2026-07-29T12:32:09+00:00

In preparation for the MarkdownLintCheck plugin being added to the repo, this change defaults the plugin to `AuditOnly` mode in each package. This allows package maintainers to enable the plugin as they see fit. Continuous-integration-options: PatchCheck.ignore-multi-package Signed-off-by: Michael Kubacki

PcAtChipsetPkg: Replace include guards with #pragma once

2026-02-23T21:01:28+00:00

Replace traditional `#ifndef`/`#define`/`#endif` include guards with `#pragma` once. `#pragma once` is a widely supported preprocessor directive that prevents header files from being included multiple times. It is supported by all toolchains used to build edk2: GCC, Clang/LLVM, and MSVC. Compared to macro-based include guards, `#pragma once`: - Eliminates the risk of macro name collisions or copy/paste errors where two headers inadvertently use the same guard macro. - Eliminate inconsistency in the way include guard macros are named (e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.). - Reduces boilerplate (three lines replaced by one). - Avoids polluting the macro namespace with guard symbols. - Can improve build times as the preprocessor can skip re-opening the file entirely, rather than re-reading it to find the matching `#endif` ("multiple-include optimization"). - Note that some compilers may already optimize traditional include guards, by recognzining the idiomatic pattern. This change is made acknowledging that overall portability of the code will technically be reduced, as `#pragma once` is not part of the C/C++ standards. However, this is considered acceptable given: 1. edk2 already defines a subset of supported compilers in BaseTools/Conf/tools_def.template, all of which have supported `#pragma once` for over two decades. 2. There have been concerns raised to the project about inconsistent include guard naming and potential macro collisions. Approximate compiler support dates: - MSVC: Supported since Visual C++ 4.2 (1996) - GCC: Supported since 3.4 (2004) (http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html) - Clang (LLVM based): Since initial release in 2007 Signed-off-by: Michael Kubacki

MdePkg: MdeLibs.dsc.inc: Apply StackCheckLibNull to All Module Types

2024-11-13T21:01:46+00:00

Now that the ResetVectors are USER_DEFINED modules, they will not be linked against StackCheckLibNull, which were the only modules causing issues. So, we can now remove the kludge we had before and the requirement for every DSC to include StackCheckLibNull for SEC modules and just apply StackCheckLibNull globally. This also changes every DSC to drop the SEC definition of StackCheckLibNull. Continuous-integration-options: PatchCheck.ignore-multi-package Signed-off-by: Oliver Smith-Denny

PcAtChipsetPkg: Write RTC time in PcRtcInit() only when it is needed

2024-11-13T09:05:56+00:00

In PcRtcInit(), it always read RTC time and then write it back. It could potentially cause two issues: 1) There is time gap between read RTC and write RTC, writing RTC time on every boot could cause RTC time drift after many reboot cycles 2) Writing RTC registers on every boot could cause some unnecessary delay, slightly impact the boot performance. The change is only writing RTC time when 1) the current RTC time is not valid or 2) the RegisterB value is changed. Signed-off-by: Chen Lin Z

PcAtChipsetPkg: Use DV bit to stop the RTC first when changing the time

2024-11-13T09:05:56+00:00

Legacy BIOS design sets only the Update Cycle Inhibit (SET) bit when changing the RTC time. Update Cycle Inhibit Bit may not be supported by the backend device (Common I2C RTC device). It could add Division Chain Select (DV) bit to stop the RTC first (Write to 0x07), Changing the RTC time and then Set the DV bit back. Signed-off-by: Di Zhang

PcAtChipsetPkg: Add StackCheckLib

2024-09-13T03:58:46+00:00

Add Null implementation of StackCheckLib. Signed-off-by: Oliver Smith-Denny

PcAtChipsetPkg/PcAtChipsetPkg.ci.yaml: Add PrEval CI config

2024-09-02T23:20:35+00:00

Adds an entry to the package's CI configuration file that enable policy 5 for stuart_pr_eval. With this Policy, all INFs used by the package are extracted from the provided DSC file and compared against the list of changed *.inf (INF) files in the PR. If there is a match, stuart_pr_eval will specify that this package is affected by the PR and needs to be tested. Signed-off-by: Joey Vagedes