In this lesson we are going to look how to embed content in HII forms dynamically.
For example it can help to display things like:
- current possible boot sources
- currently present PCI devices
- currently present memory
- ...
All these things are determined in the UEFI boot process and can differ from boot to boot depending on the current hardware configuration. Therefore if you want to add such information to the HII Forms you need to do it dynamically.
For this operation EDKII uses labels mechanics.
But first let's create HIIFormLabel application with an empty form. For simplicity we wouldn't use any storage in this example (as we would embed simple elements that don't use storage at all).
Here is code for the driver that adds an empty form.
UefiLessonsPkg/HIIFormLabel/HIIFormLabel.inf:
[Defines]
INF_VERSION = 1.25
BASE_NAME = HIIFormLabel
FILE_GUID = a869c42c-fd49-469d-b6ab-b37569c0e90d
MODULE_TYPE = UEFI_DRIVER
VERSION_STRING = 1.0
ENTRY_POINT = HIIFormLabelEntryPoint
UNLOAD_IMAGE = HIIFormLabelUnload
[Sources]
HIIFormLabel.c
Strings.uni
Form.vfr
[Packages]
MdePkg/MdePkg.dec
MdeModulePkg/MdeModulePkg.dec
[LibraryClasses]
UefiDriverEntryPoint
UefiLib
HiiLib
UefiLessonsPkg/HIIFormLabel/HIIFormLabel.c:
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Library/HiiLib.h>
#include "Data.h"
#include <Guid/MdeModuleHii.h>
extern UINT8 FormBin[];
EFI_HII_HANDLE mHiiHandle = NULL;
EFI_STATUS
EFIAPI
HIIFormLabelUnload (
EFI_HANDLE ImageHandle
)
{
if (mHiiHandle != NULL)
HiiRemovePackages(mHiiHandle);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
HIIFormLabelEntryPoint (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
mHiiHandle = HiiAddPackages(
&gEfiCallerIdGuid,
NULL,
HIIFormLabelStrings,
FormBin,
NULL
);
if (mHiiHandle == NULL) {
return EFI_OUT_OF_RESOURCES;
}
return EFI_SUCCESS;
UefiLessonsPkg/HIIFormLabel/Data.h:
#ifndef _DATA_H_
#define _DATA_H_
#define FORMSET_GUID {0x29caf8e0, 0x2788, 0x4e1c, {0xb6, 0x15, 0x5b, 0xf8, 0x2f, 0x06, 0x7a, 0xa5}}
#endif
UefiLessonsPkg/HIIFormLabel/Form.vfr:
#include "Data.h"
formset
guid = FORMSET_GUID,
title = STRING_TOKEN(FORMSET_TITLE),
help = STRING_TOKEN(FORMSET_HELP),
form
formid = 1,
title = STRING_TOKEN(FORMID1_TITLE);
endform;
endformset;
UefiLessonsPkg/HIIFormLabel/Strings.uni:
#langdef en-US "English"
#string FORMSET_TITLE #language en-US "Simple Formset"
#string FORMSET_HELP #language en-US "This is a very simple formset"
#string FORMID1_TITLE #language en-US "Simple Form"
All this code would give us this form:
Now let's try add content dynamically to our form.
Add two label elements to our form in UefiLessonsPkg/HIIFormDataElements/Form.vfr:
formset
guid = FORMSET_GUID,
title = STRING_TOKEN(FORMSET_TITLE),
help = STRING_TOKEN(FORMSET_HELP),
form
formid = 1,
title = STRING_TOKEN(FORMID1_TITLE);
label LABEL_START;
label LABEL_END;
endform;
endformset;
These two elements define the start and the end of the section for the dynamic content.
Values under LABEL_START and LABEL_END are just UINT16 numbers. Place some defines for them to the UefiLessonsPkg/HIIFormDataElements/Data.h:
#define LABEL_START 0x1111
#define LABEL_END 0x2222
The actual label numbers are not important. The only limitation is that label numers must be unique in a scope of a target form.
Build module and look at the IFR Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/HIIFormDataElements/HIIFormDataElements/DEBUG/Form.lst:
label 0x1111;
>00000117: 5F 15 35 17 0B 0F A0 87 93 41 B2 66 53 8C 38 AF 48 CE 00 11 11
label 0x2222;
>0000012C: 5F 15 35 17 0B 0F A0 87 93 41 B2 66 53 8C 38 AF 48 CE 00 22 22
Labels are encoded with a help of EFI_IFR_GUID_OP opcode. This opcode helps vendors to add new IFR opcodes that are not defined in the UEFI specification. This is a method for UEFI specification extension.
EFI_IFR_GUID
Summary:
A GUIDed operation. This op-code serves as an extensible op-code which can be defined by the Guid value to have various functionality. It should be noted that IFR browsers or scripts which cannot interpret the meaning of this GUIDed op-code will skip it.
Prototype:
#define EFI_IFR_GUID_OP 0x5F
typedef struct _EFI_IFR_GUID {
EFI_IFR_OP_HEADER Header;
EFI_GUID Guid;
//Optional Data Follows
} EFI_IFR_GUID;
Parameters:
Header The sequence that defines the type of opcode as well as the length of the opcode being defined.
For this tag, Header.OpCode = EFI_IFR_GUID_OP
Guid The GUID value for this op-code. This field is intended to define a particular type of special-purpose function,
and the format of the data which immediately follows the Guid field (if any) is defined by that particular GUID.
If you parse our binary data you could see that in our case Guid is equal to:
35 17 0B 0F A0 87 93 41 B2 66 53 8C 38 AF 48 CE
This value defines a format of all the rest of the opcode data that follows next until the opcode end (which is determined by Header.Length). In this case it is 00 11 11 or 00 22 22.
The GUID in the IFR is defined in the ./MdeModulePkg/MdeModulePkg.dec:
gEfiIfrTianoGuid = { 0xf0b1735, 0x87a0, 0x4193, {0xb2, 0x66, 0x53, 0x8c, 0x38, 0xaf, 0x48, 0xce }}
Or in the ./MdeModulePkg/Include/Guid/MdeModuleHii.h:
#define EFI_IFR_TIANO_GUID \
{ 0xf0b1735, 0x87a0, 0x4193, {0xb2, 0x66, 0x53, 0x8c, 0x38, 0xaf, 0x48, 0xce} }
EDKII has several special IFR opcodes. All of them are defined under the same EFI_IFR_TIANO_GUID. To differ them between each other the first byte after the GUID defines an opcode:
///
/// EDKII implementation extension opcodes, new extension can be added here later.
///
#define EFI_IFR_EXTEND_OP_LABEL 0x0
#define EFI_IFR_EXTEND_OP_BANNER 0x1
#define EFI_IFR_EXTEND_OP_TIMEOUT 0x2
#define EFI_IFR_EXTEND_OP_CLASS 0x3
#define EFI_IFR_EXTEND_OP_SUBCLASS 0x4
In our case the next byte is 0x00 which corresponds to the EFI_IFR_EXTEND_OP_LABEL.
In this case the full opcode is defined with this structure:
///
/// Label opcode.
///
typedef struct _EFI_IFR_GUID_LABEL {
EFI_IFR_OP_HEADER Header;
///
/// EFI_IFR_TIANO_GUID.
///
EFI_GUID Guid; // EFI_IFR_TIANO_GUID
///
/// EFI_IFR_EXTEND_OP_LABEL.
///
UINT8 ExtendOpCode; // EFI_IFR_EXTEND_OP_LABEL = 0x0
///
/// Label Number.
///
UINT16 Number;
} EFI_IFR_GUID_LABEL;
To insert content from the C code into the section defined by labels we need to utilize HiiUpdateForm function from the HiiLib
https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Include/Library/HiiLib.h
/**
This function updates a form that has previously been registered with the HII
Database. This function will perform at most one update operation.
The form to update is specified by Handle, FormSetGuid, and FormId. Binary
comparisons of IFR opcodes are performed from the beginning of the form being
updated until an IFR opcode is found that exactly matches the first IFR opcode
specified by StartOpCodeHandle. The following rules are used to determine if
an insert, replace, or delete operation is performed:
1) If no matches are found, then NULL is returned.
2) If a match is found, and EndOpCodeHandle is NULL, then all of the IFR opcodes
from StartOpCodeHandle except the first opcode are inserted immediately after
the matching IFR opcode in the form to be updated.
3) If a match is found, and EndOpCodeHandle is not NULL, then a search is made
from the matching IFR opcode until an IFR opcode exactly matches the first
IFR opcode specified by EndOpCodeHandle. If no match is found for the first
IFR opcode specified by EndOpCodeHandle, then NULL is returned. If a match
is found, then all of the IFR opcodes between the start match and the end
match are deleted from the form being updated and all of the IFR opcodes
from StartOpCodeHandle except the first opcode are inserted immediately after
the matching start IFR opcode. If StartOpCcodeHandle only contains one
IFR instruction, then the result of this operation will delete all of the IFR
opcodes between the start end matches.
If HiiHandle is NULL, then ASSERT().
If StartOpCodeHandle is NULL, then ASSERT().
@param[in] HiiHandle The HII Handle of the form to update.
@param[in] FormSetGuid The Formset GUID of the form to update. This
is an optional parameter that may be NULL.
If it is NULL, all FormSet will be updated.
@param[in] FormId The ID of the form to update.
@param[in] StartOpCodeHandle An OpCode Handle that contains the set of IFR
opcodes to be inserted or replaced in the form.
The first IFR instruction in StartOpCodeHandle
is used to find matching IFR opcode in the
form.
@param[in] EndOpCodeHandle An OpCcode Handle that contains the IFR opcode
that marks the end of a replace operation in
the form. This is an optional parameter that
may be NULL. If it is NULL, then the IFR
opcodes specified by StartOpCodeHandle are
inserted into the form.
@retval EFI_OUT_OF_RESOURCES Not enough memory resources are allocated.
@retval EFI_NOT_FOUND The following cases will return EFI_NOT_FOUND:
1) The form specified by HiiHandle, FormSetGuid,
and FormId could not be found in the HII Database.
2) No IFR opcodes in the target form match the first
IFR opcode in StartOpCodeHandle.
3) EndOpCOde is not NULL, and no IFR opcodes in the
target form following a matching start opcode match
the first IFR opcode in EndOpCodeHandle.
@retval EFI_SUCCESS The matched form is updated by StartOpcode.
**/
EFI_STATUS
EFIAPI
HiiUpdateForm (
IN EFI_HII_HANDLE HiiHandle,
IN EFI_GUID *FormSetGuid OPTIONAL,
IN EFI_FORM_ID FormId,
IN VOID *StartOpCodeHandle,
IN VOID *EndOpCodeHandle OPTIONAL
);
As you can see this function needs two opcode handles:
StartOpCodeHandle- handle to opcode buffer that contains IFR that marks a start of a replace section + all the opcodes that are needed to be inserted,EndOpCodeHandle- handle to opcode buffer that contains IFR that marks an end of a replace section
How to create these OpCode Handles? HiiLib has a special function for that:
/**
Allocates and returns a new OpCode Handle. OpCode Handles must be freed with
HiiFreeOpCodeHandle().
@retval NULL There are not enough resources to allocate a new OpCode Handle.
@retval Other A new OpCode handle.
**/
VOID *
EFIAPI
HiiAllocateOpCodeHandle (
VOID
);
The important thing to note here is that this function doesn't accept any size. Because in this operation the buffer is always fixed. HiiAllocateOpCodeHandle returns a pointer to the newly allocated structure HII_LIB_OPCODE_BUFFER that is defined as follow:
#define HII_LIB_OPCODE_ALLOCATION_SIZE 0x200 // (=512)
typedef struct {
UINT8 *Buffer; // Pointer to newly allocated buffer of HII_LIB_OPCODE_ALLOCATION_SIZE bytes
UINTN BufferSize;
UINTN Position;
} HII_LIB_OPCODE_BUFFER;
All our dynamically allocated opcodes should fit into the preallocated buffer.
Off course we need to free all the buffers allocated with the HiiAllocateOpCodeHandle:
/**
Frees an OpCode Handle that was previously allocated with HiiAllocateOpCodeHandle().
When an OpCode Handle is freed, all of the opcodes associated with the OpCode
Handle are also freed.
If OpCodeHandle is NULL, then ASSERT().
@param[in] OpCodeHandle The handle to the buffer of opcodes.
**/
VOID
EFIAPI
HiiFreeOpCodeHandle (
VOID *OpCodeHandle
);
So in our driver we should add this code:
VOID* StartOpCodeHandle = HiiAllocateOpCodeHandle();
VOID* EndOpCodeHandle = HiiAllocateOpCodeHandle();
<...> // fill OpCode Handles
EFI_GUID formsetGuid = FORMSET_GUID;
EFI_STATUS Status = HiiUpdateForm(
mHiiHandle,
&formsetGuid,
0x1,
StartOpCodeHandle,
EndOpCodeHandle
);
if (EFI_ERROR(Status)) {
Print(L"Error! HiiUpdateForm returned = %r\n", Status);
}
HiiFreeOpCodeHandle(StartOpCodeHandle);
HiiFreeOpCodeHandle(EndOpCodeHandle);
return Status;
Now we need to create correct data under StartOpCodeHandle and EndOpCodeHandle. First we need to add label IFR to them. For this task we can utilize HiiCreateGuidOpCode function:
/**
Create EFI_IFR_GUID opcode.
If OpCodeHandle is NULL, then ASSERT().
If Guid is NULL, then ASSERT().
If OpCodeSize < sizeof (EFI_IFR_GUID), then ASSERT().
@param[in] OpCodeHandle Handle to the buffer of opcodes.
@param[in] Guid Pointer to EFI_GUID of this guided opcode.
@param[in] GuidOpCode Pointer to an EFI_IFR_GUID opcode. This is an
optional parameter that may be NULL. If this
parameter is NULL, then the GUID extension
region of the created opcode is filled with zeros.
If this parameter is not NULL, then the GUID
extension region of GuidData will be copied to
the GUID extension region of the created opcode.
@param[in] OpCodeSize The size, in bytes, of created opcode. This value
must be >= sizeof(EFI_IFR_GUID).
@retval NULL There is not enough space left in Buffer to add the opcode.
@retval Other A pointer to the created opcode.
**/
UINT8 *
EFIAPI
HiiCreateGuidOpCode (
IN VOID *OpCodeHandle,
IN CONST EFI_GUID *Guid,
IN CONST VOID *GuidOpCode OPTIONAL,
IN UINTN OpCodeSize
)
This function returns a pointer to the opcode buffer. In our case it is a buffer that starts with a EFI_IFR_GUID_LABEL opcode. So we need to cast the buffer to the EFI_IFR_GUID_LABEL structure and fill it with correct data. If HiiCreateGuidOpCode returns NULL we need to report an error and free all the previously allocated resources:
EFI_IFR_GUID_LABEL* StartLabel = (EFI_IFR_GUID_LABEL*) HiiCreateGuidOpCode(StartOpCodeHandle,
&gEfiIfrTianoGuid,
NULL,
sizeof(EFI_IFR_GUID_LABEL)
);
if (StartLabel == NULL) {
Print(L"Error! Can't create StartLabel opcode, not enough space\n");
HiiRemovePackages(mHiiHandle);
return EFI_BUFFER_TOO_SMALL;
}
StartLabel->ExtendOpCode = EFI_IFR_EXTEND_OP_LABEL;
StartLabel->Number = LABEL_START;
EFI_IFR_GUID_LABEL* EndLabel = (EFI_IFR_GUID_LABEL*) HiiCreateGuidOpCode(EndOpCodeHandle,
&gEfiIfrTianoGuid,
NULL,
sizeof(EFI_IFR_GUID_LABEL)
);
if (EndLabel == NULL) {
Print(L"Error! Can't create Text opcode, not enough space\n");
HiiFreeOpCodeHandle(StartOpCodeHandle);
HiiRemovePackages(mHiiHandle);
return EFI_BUFFER_TOO_SMALL;
}
EndLabel->ExtendOpCode = EFI_IFR_EXTEND_OP_LABEL;
EndLabel->Number = LABEL_END;
As we are using gEfiIfrTianoGuid here, don't forget to add #include <Guid/MdeModuleHii.h> to our code and add proper Guids section to the INF file:
[Guids]
gEfiIfrTianoGuid
Our final task is to embed new code to the IFR. So besides the markers (=labels) we need to add actually new IFR codes to the buffer referenced by the StartOpCodeHandle. Let's add a VFR text element with a help of a HiiCreateTextOpCode function:
/**
Create EFI_IFR_TEXT_OP opcode.
If OpCodeHandle is NULL, then ASSERT().
@param[in] OpCodeHandle Handle to the buffer of opcodes.
@param[in] Prompt String ID for Prompt.
@param[in] Help String ID for Help.
@param[in] TextTwo String ID for TextTwo.
@retval NULL There is not enough space left in Buffer to add the opcode.
@retval Other A pointer to the created opcode.
**/
UINT8 *
EFIAPI
HiiCreateTextOpCode (
IN VOID *OpCodeHandle,
IN EFI_STRING_ID Prompt,
IN EFI_STRING_ID Help,
IN EFI_STRING_ID TextTwo
);
As you can see this function needs EFI_STRING_ID for the new text element. As we are generating our new element dynamically, let's also add new strings dynamically to the HII database:
For this task we can utilize HiiSetString function from the https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Library/UefiHiiLib/HiiString.c:
/**
This function create a new string in String Package or updates an existing
string in a String Package. If StringId is 0, then a new string is added to
a String Package. If StringId is not zero, then a string in String Package is
updated. If SupportedLanguages is NULL, then the string is added or updated
for all the languages that the String Package supports. If SupportedLanguages
is not NULL, then the string is added or updated for the set of languages
specified by SupportedLanguages.
If HiiHandle is NULL, then ASSERT().
If String is NULL, then ASSERT().
@param[in] HiiHandle A handle that was previously registered in the
HII Database.
@param[in] StringId If zero, then a new string is created in the
String Package associated with HiiHandle. If
non-zero, then the string specified by StringId
is updated in the String Package associated
with HiiHandle.
@param[in] String A pointer to the Null-terminated Unicode string
to add or update in the String Package associated
with HiiHandle.
@param[in] SupportedLanguages A pointer to a Null-terminated ASCII string of
language codes. If this parameter is NULL, then
String is added or updated in the String Package
associated with HiiHandle for all the languages
that the String Package supports. If this
parameter is not NULL, then then String is added
or updated in the String Package associated with
HiiHandle for the set oflanguages specified by
SupportedLanguages. The format of
SupportedLanguages must follow the language
format assumed the HII Database.
@retval 0 The string could not be added or updated in the String Package.
@retval Other The EFI_STRING_ID of the newly added or updated string.
**/
EFI_STRING_ID
EFIAPI
HiiSetString (
IN EFI_HII_HANDLE HiiHandle,
IN EFI_STRING_ID StringId OPTIONAL,
IN CONST EFI_STRING String,
IN CONST CHAR8 *SupportedLanguages OPTIONAL
)
With this function we can create new strings as simple as this:
EFI_STRING_ID text_prompt = HiiSetString(mHiiHandle,
0,
L"Text prompt",
NULL);
EFI_STRING_ID text_help = HiiSetString(mHiiHandle,
0,
L"Text help",
NULL);
Now we can use HiiCreateTextOpCode function to add more opcodes to the opcode buffer referenced by the StartOpCodeHandle:
UINT8* Result = HiiCreateTextOpCode(StartOpCodeHandle,
text_prompt,
text_help,
0);
if (Result == NULL) {
Print(L"Error! Can't create Text opcode, not enough space\n");
HiiFreeOpCodeHandle(StartOpCodeHandle);
HiiFreeOpCodeHandle(EndOpCodeHandle);
HiiRemovePackages(mHiiHandle);
return EFI_BUFFER_TOO_SMALL;
}
Let's add another text element for our example. Once again the HiiCreateTextOpCode would use the same StartOpCodeHandle:
text_prompt = HiiSetString(mHiiHandle,
0,
L"Another text prompt",
NULL);
text_help = HiiSetString(mHiiHandle,
0,
L"Another text help",
NULL);
Result = HiiCreateTextOpCode(StartOpCodeHandle,
text_prompt,
text_help,
0);
if (Result == NULL) {
Print(L"Error! Can't create Text opcode, not enough space\n");
HiiFreeOpCodeHandle(StartOpCodeHandle);
HiiFreeOpCodeHandle(EndOpCodeHandle);
HiiRemovePackages(mHiiHandle);
return EFI_BUFFER_TOO_SMALL;
}
Now when we have StartOpCodeHandle and EndOpCodeHandle filled, HiiUpdateForm call should succeed. So let's build and load our driver.
If you look at our form, you will see that now that it has 2 text elements like we have intended:
In our example we've used HiiCreateTextOpCode function to create EFI_IFR_TEXT_OP opcode (i.e. text element). But HiiLib offers many functions to create all kinds of elements. Most of them we are already know:
https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Include/Library/HiiLib.h
https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Library/UefiHiiLib/HiiLib.c
HiiCreateSubTitleOpCode EFI_IFR_SUBTITLE_OP
HiiCreateCheckBoxOpCode EFI_IFR_CHECKBOX_OP
HiiCreateTextOpCode EFI_IFR_TEXT_OP
HiiCreateNumericOpCode EFI_IFR_NUMERIC_OP
HiiCreateStringOpCode EFI_IFR_STRING_OP
HiiCreateDateOpCode EFI_IFR_DATE_OP
HiiCreateTimeOpCode EFI_IFR_TIME_OP
HiiCreateOneOfOpCode EFI_IFR_ONE_OF_OP
HiiCreateOneOfOptionOpCode EFI_IFR_ONE_OF_OPTION_OP
HiiCreateOrderedListOpCode EFI_IFR_ORDERED_LIST_OP
HiiCreateDefaultOpCode EFI_IFR_DEFAULT_OP
HiiCreateGuidOpCode EFI_IFR_GUID
HiiCreateActionOpCode EFI_IFR_ACTION_OP
HiiCreateGotoOpCode EFI_IFR_REF_OP
HiiCreateGotoExOpCode EFI_IFR_REF_OP, EFI_IFR_REF2_OP, EFI_IFR_REF3_OP and EFI_IFR_REF4_OP
HiiCreateEndOpCode EFI_IFR_END_OP
And if this is not enough for you HiiLib library has a function to add raw opcode buffer:
/**
Append raw opcodes to an OpCodeHandle.
If OpCodeHandle is NULL, then ASSERT().
If RawBuffer is NULL, then ASSERT();
@param[in] OpCodeHandle Handle to the buffer of opcodes.
@param[in] RawBuffer Buffer of opcodes to append.
@param[in] RawBufferSize The size, in bytes, of Buffer.
@retval NULL There is not enough space left in Buffer to add the opcode.
@retval Other A pointer to the appended opcodes.
**/
UINT8 *
EFIAPI
HiiCreateRawOpCodes (
IN VOID *OpCodeHandle,
IN UINT8 *RawBuffer,
IN UINTN RawBufferSize
)