MdeModulePkg\Core\Pei\Dispatcher\Dispatcher.c
/**
Conduct PEIM dispatch.
@param SecCoreData Points to a data structure containing information about the PEI core's operating
environment, such as the size and location of temporary RAM, the stack location and
the BFV location.
@param Private Pointer to the private data passed in from caller
**/
VOID
PeiDispatcher (
IN CONST EFI_SEC_PEI_HAND_OFF *SecCoreData,
IN PEI_CORE_INSTANCE *Private
)
进去这个函数之后，因为刚开始内存并没有准备好，所以 (Private->PeiMemoryInstalled) 这个条件不会满足，会进入下面的do … while 循环。
//
// This is the main dispatch loop. It will search known FVs for PEIMs and
// attempt to dispatch them. If any PEIM gets dispatched through a single
// pass of the dispatcher, it will start over from the BFV again to see
// if any new PEIMs dependencies got satisfied. With a well ordered
// FV where PEIMs are found in the order their dependencies are also
// satisfied, this dispatcher should run only once.
//
跳转到DiscoverPeimsAndOrderWithApriori() 函数中
if (Private->CurrentPeimCount == 0) {
//
// When going through each FV, at first, search Apriori file to
// reorder all PEIMs to ensure the PEIMs in Apriori file to get
// dispatch at first.
//
DiscoverPeimsAndOrderWithApriori (Private, CoreFvHandle);
}
这个函数的作用是找到所有的 PEIM以及Apriori 文件。
/**
Discover all PEIMs and optional Apriori file in one FV. There is at most one
Apriori file in one FV.
@param Private Pointer to the private data passed in from caller
@param CoreFileHandle The instance of PEI_CORE_FV_HANDLE.
**/
VOID
DiscoverPeimsAndOrderWithApriori (
IN PEI_CORE_INSTANCE *Private,
IN PEI_CORE_FV_HANDLE *CoreFileHandle
)
函数中有一个 DEBUG 输出如下：
DEBUG ((
DEBUG_INFO,
"%a(): Found 0x%x PEI FFS files in the %dth FV\n",
__FUNCTION__,
PeimCount,
Private->CurrentPeimFvCount
));
对应的串口 Log 中有如下字样，就是说在找到了7个 PEIM
DiscoverPeimsAndOrderWithApriori(): Found 0x7 PEI FFS files in the 0th FV
为了更好的观测，加入代码，输出它找到的 PEIM 的 GUID:
for (Index = 0; Index < PeimCount; Index++) {
//
// Make an array of file name GUIDs that matches the FileHandle array so we can convert
// quickly from file name to file handle
//
Status = FvPpi->GetFileInfo (FvPpi, TempFileHandles[Index], &FileInfo);
ASSERT_EFI_ERROR (Status);
CopyMem (&TempFileGuid[Index], &FileInfo.FileName, sizeof(EFI_GUID));
DEBUG ((DEBUG_INFO , "%g\n", FileInfo.FileName));
}
//
// For PEIM driver, Load its entry point
//
Status = PeiLoadImage (
PeiServices,
PeimFileHandle,
PEIM_STATE_NOT_DISPATCHED,
&EntryPoint,
&AuthenticationState
);
/**
Routine to load image file for subsequent execution by LoadFile Ppi.
If any LoadFile Ppi is not found, the build-in support function for the PE32+/TE
XIP image format is used.
@param PeiServices - An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation
@param FileHandle - Pointer to the FFS file header of the image.
@param PeimState - The dispatch state of the input PEIM handle.
@param EntryPoint - Pointer to entry point of specified image file for output.
@param AuthenticationState - Pointer to attestation authentication state of image.
@retval EFI_SUCCESS - Image is successfully loaded.
@retval EFI_NOT_FOUND - Fail to locate necessary PPI
@retval Others - Fail to load file.
**/
EFI_STATUS
PeiLoadImage (
IN CONST EFI_PEI_SERVICES **PeiServices,
IN EFI_PEI_FILE_HANDLE FileHandle,
IN UINT8 PeimState,
OUT EFI_PHYSICAL_ADDRESS *EntryPoint,
OUT UINT32 *AuthenticationState
)
/**
Loads a PEIM into memory for subsequent execution. If there are compressed
images or images that need to be relocated into memory for performance reasons,
this service performs that transformation.
@param PeiServices An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation
@param FileHandle Pointer to the FFS file header of the image.
@param ImageAddressArg Pointer to PE/TE image.
@param ImageSizeArg Size of PE/TE image.
@param EntryPoint Pointer to entry point of specified image file for output.
@param AuthenticationState - Pointer to attestation authentication state of image.
@retval EFI_SUCCESS Image is successfully loaded.
@retval EFI_NOT_FOUND Fail to locate necessary PPI.
@retval EFI_UNSUPPORTED Image Machine Type is not supported.
@retval EFI_WARN_BUFFER_TOO_SMALL
There is not enough heap to allocate the requested size.
This will not prevent the XIP image from being invoked.
**/
EFI_STATUS
PeiLoadImageLoadImage (
IN CONST EFI_PEI_SERVICES **PeiServices,
IN EFI_PEI_FILE_HANDLE FileHandle,
OUT EFI_PHYSICAL_ADDRESS *ImageAddressArg, OPTIONAL
OUT UINT64 *ImageSizeArg, OPTIONAL
OUT EFI_PHYSICAL_ADDRESS *EntryPoint,
OUT UINT32 *AuthenticationState
)
CSME 算是 Intel X86 PC 上最神秘的部分了，本文根据 us-19-Hasarfaty-Behind-The-Scenes-Of-Intel-Security-And-Manageability-Engine 一文写成。讲述内容无法证伪，各位随便听听即可，了解这些能够帮助BIOS 工程师更好的理解一些操作的实现。文章基于 Intel 第八代第九代CPU（Coffee Lake 和 Whiskey Lake）进行描述。
In this position, you will be part of the Firmware Integration and Validation (FIV) Team within SATG responsible for UEFI Firmware/BIOS quality assurance on Intel server platforms. Behavioral traits for this position include: validation infrastructure and test case development, in-depth bug investigation and fix, good communication and problem solving skills, multi-tasking, self-motivation and the ability to collaborate with internal/external stakeholders.
The candidate’s responsibilities will include but not limit to:
Design and develop framework and utility for IP/module level validation according to module specifications, such as PRD, HAS etc;
Be responsible for test case development according to product requirement for server BIOS;
Be responsible for the test execution on Intel server platform for BIOS and platform FW test;
Work with team members to investigate test failures using variety of debug tools to perform evaluation of the issue and identify the failure to component or code level;
Be responsible for developing and sustaining the automation test framework, test scripts and utilities; deploy and maintain automation test cases, analyze test reports and logs.
Qualifications:
The candidate should possess a Master or a Bachelor degree in computer science, Computer Engineering or a related field, with at least 5 years industrial experience on BIOS development or testing. Additional qualifications include:
Solid knowledge of BIOS and UEFI Firmware;
Deep understanding of server architecture of both HW and SW;
Deep understanding of industry specification such as UEFI/ACPI/SMBIOS/TPM/etc;
Software development skills with different programming languages include but not limited to: C/C++/C#, Python, Windows Batch Script, JavaScript, etc;
Solid experience of software testing process and methodologies;
Skilled in BIOS test case development and issue debugging;
Good English communication skill in reading and writing, good speaking capability;
Knowledge of Linux Kernel or device driver development is a plus.
除了SPD 中给出的参数，在内存初始化时，CPU 还需要有针对性的获得一些参数，而这些参数和生产制造环境温度等等情况有关系（听起来时玄学）。因此，在开机的时候内存控制器会进行一个 Memory Training 的动作。比如，当前内存槽上有2根内存，但是因为线长的原因，同样的信号到达内存的时间不同。在开机的时候，内存控制器就发出一个信号分别给两个内存，内存收到信号后发送一个应答。根据回复的时间不同，内存控制器可以取得一个能够让两个内存都工作正常的时序。当然，这里只是非常粗略的介绍，实际上这个过程非常复杂，耗时也会很久。而Training完成后，BIOS会将取得的参数保存在SPI NOR 上。这也是为什么第一次刷过BIOS之后开机要很久的原因。
一些情况下，我们希望强制进行 Memory Training，通常的方法是进行 Clear CMOS。这次提供了一个 Windows 工具，运行之后重启，SoC 即会进行完整的 Memory Training。
