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dtcompile.c revision 1.1.1.19
      1 /******************************************************************************
      2  *
      3  * Module Name: dtcompile.c - Front-end for data table compiler
      4  *
      5  *****************************************************************************/
      6 
      7 /*
      8  * Copyright (C) 2000 - 2022, Intel Corp.
      9  * All rights reserved.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions, and the following disclaimer,
     16  *    without modification.
     17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
     18  *    substantially similar to the "NO WARRANTY" disclaimer below
     19  *    ("Disclaimer") and any redistribution must be conditioned upon
     20  *    including a substantially similar Disclaimer requirement for further
     21  *    binary redistribution.
     22  * 3. Neither the names of the above-listed copyright holders nor the names
     23  *    of any contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * Alternatively, this software may be distributed under the terms of the
     27  * GNU General Public License ("GPL") version 2 as published by the Free
     28  * Software Foundation.
     29  *
     30  * NO WARRANTY
     31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
     40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     41  * POSSIBILITY OF SUCH DAMAGES.
     42  */
     43 
     44 #define _DECLARE_DT_GLOBALS
     45 
     46 #include "aslcompiler.h"
     47 
     48 #define _COMPONENT          DT_COMPILER
     49         ACPI_MODULE_NAME    ("dtcompile")
     50 
     51 static char                 VersionString[9];
     52 
     53 
     54 /* Local prototypes */
     55 
     56 void
     57 DtInitialize (
     58     void);
     59 
     60 static ACPI_STATUS
     61 DtCompileDataTable (
     62     DT_FIELD                **Field);
     63 
     64 static void
     65 DtInsertCompilerIds (
     66     DT_FIELD                *FieldList);
     67 
     68 
     69 /******************************************************************************
     70  *
     71  * FUNCTION:    DtDoCompile
     72  *
     73  * PARAMETERS:  None
     74  *
     75  * RETURN:      Status
     76  *
     77  * DESCRIPTION: Main entry point for the data table compiler.
     78  *
     79  * Note: Assumes AslGbl_Files[ASL_FILE_INPUT] is initialized and the file is
     80  *          open at seek offset zero.
     81  *
     82  *****************************************************************************/
     83 
     84 ACPI_STATUS
     85 DtDoCompile (
     86     void)
     87 {
     88     ACPI_STATUS             Status;
     89     UINT8                   Event;
     90     DT_FIELD                *FieldList;
     91     ASL_GLOBAL_FILE_NODE    *FileNode;
     92 
     93 
     94     /* Initialize globals */
     95 
     96     DtInitialize ();
     97 
     98     /* Preprocessor */
     99 
    100     if (AslGbl_PreprocessFlag)
    101     {
    102         /* Preprocessor */
    103 
    104         Event = UtBeginEvent ("Preprocess input file");
    105         PrDoPreprocess ();
    106         UtEndEvent (Event);
    107 
    108         if (AslGbl_PreprocessOnly)
    109         {
    110             return (AE_OK);
    111         }
    112     }
    113 
    114     /* Compile the parse tree */
    115 
    116     if (AslGbl_DtLexBisonPrototype)
    117     {
    118         Event = UtBeginEvent ("Parse data table in prototype mode");
    119 
    120         DtCompilerInitLexer (AslGbl_Files[ASL_FILE_INPUT].Handle);
    121         DtCompilerParserparse ();
    122         FieldList = AslGbl_FieldList;
    123         DtCompilerTerminateLexer ();
    124 
    125         UtEndEvent (Event);
    126     }
    127     else
    128     {
    129         /*
    130          * Scan the input file (file is already open) and
    131          * build the parse tree
    132          */
    133         Event = UtBeginEvent ("Scan and parse input file");
    134         FieldList = DtScanFile (AslGbl_Files[ASL_FILE_INPUT].Handle);
    135         UtEndEvent (Event);
    136     }
    137 
    138     /* Did the parse tree get successfully constructed? */
    139 
    140     if (!FieldList)
    141     {
    142         /* TBD: temporary error message. Msgs should come from function above */
    143 
    144         DtError (ASL_ERROR, ASL_MSG_SYNTAX, NULL,
    145             "Input file does not appear to be an ASL or data table source file");
    146 
    147         return (AE_ERROR);
    148     }
    149 
    150     Event = UtBeginEvent ("Compile parse tree");
    151 
    152     Status = DtCompileDataTable (&FieldList);
    153     UtEndEvent (Event);
    154 
    155     FileNode = FlGetCurrentFileNode ();
    156 
    157     FileNode->TotalLineCount = AslGbl_CurrentLineNumber;
    158     FileNode->OriginalInputFileSize = AslGbl_InputByteCount;
    159     DbgPrint (ASL_PARSE_OUTPUT, "Line count: %u input file size: %u\n",
    160             FileNode->TotalLineCount, FileNode->OriginalInputFileSize);
    161 
    162     if (ACPI_FAILURE (Status))
    163     {
    164         FileNode->ParserErrorDetected = TRUE;
    165 
    166         /* TBD: temporary error message. Msgs should come from function above */
    167 
    168         DtError (ASL_ERROR, ASL_MSG_SYNTAX, NULL,
    169             "Could not compile input file");
    170 
    171         return (Status);
    172     }
    173 
    174     /* Create/open the binary output file */
    175 
    176     AslGbl_Files[ASL_FILE_AML_OUTPUT].Filename = NULL;
    177     Status = FlOpenAmlOutputFile (AslGbl_OutputFilenamePrefix);
    178     if (ACPI_FAILURE (Status))
    179     {
    180         return (Status);
    181     }
    182 
    183     /* Write the binary, then the optional hex file */
    184 
    185     DtOutputBinary (AslGbl_RootTable);
    186     HxDoHexOutput ();
    187     DtWriteTableToListing ();
    188 
    189     /* Save the compile time statistics to the current file node */
    190 
    191     FileNode->TotalFields = AslGbl_InputFieldCount;
    192     FileNode->OutputByteLength = AslGbl_TableLength;
    193 
    194     return (Status);
    195 }
    196 
    197 
    198 /******************************************************************************
    199  *
    200  * FUNCTION:    DtInitialize
    201  *
    202  * PARAMETERS:  None
    203  *
    204  * RETURN:      Status
    205  *
    206  * DESCRIPTION: Initialize data table compiler globals. Enables multiple
    207  *              compiles per invocation.
    208  *
    209  *****************************************************************************/
    210 
    211 void
    212 DtInitialize (
    213     void)
    214 {
    215 
    216 
    217     AcpiUtSetIntegerWidth (2); /* Set width to 64 bits */
    218 
    219     AslGbl_FieldList = NULL;
    220     AslGbl_RootTable = NULL;
    221     AslGbl_SubtableStack = NULL;
    222 
    223     sprintf (VersionString, "%X", (UINT32) ACPI_CA_VERSION);
    224     return;
    225 }
    226 
    227 
    228 /******************************************************************************
    229  *
    230  * FUNCTION:    DtInsertCompilerIds
    231  *
    232  * PARAMETERS:  FieldList           - Current field list pointer
    233  *
    234  * RETURN:      None
    235  *
    236  * DESCRIPTION: Insert the IDs (Name, Version) of the current compiler into
    237  *              the original ACPI table header.
    238  *
    239  *****************************************************************************/
    240 
    241 static void
    242 DtInsertCompilerIds (
    243     DT_FIELD                *FieldList)
    244 {
    245     DT_FIELD                *Next;
    246     UINT32                  i;
    247 
    248 
    249     /*
    250      * Don't insert current compiler ID if requested. Used for compiler
    251      * debug/validation only.
    252      */
    253     if (AslGbl_UseOriginalCompilerId)
    254     {
    255         return;
    256     }
    257 
    258     /* Walk to the Compiler fields at the end of the header */
    259 
    260     Next = FieldList;
    261     for (i = 0; i < 7; i++)
    262     {
    263         Next = Next->Next;
    264     }
    265 
    266     Next->Value = ASL_CREATOR_ID;
    267     Next->Flags = DT_FIELD_NOT_ALLOCATED;
    268 
    269     Next = Next->Next;
    270     Next->Value = VersionString;
    271     Next->Flags = DT_FIELD_NOT_ALLOCATED;
    272 }
    273 
    274 
    275 /******************************************************************************
    276  *
    277  * FUNCTION:    DtCompileDataTable
    278  *
    279  * PARAMETERS:  FieldList           - Current field list pointer
    280  *
    281  * RETURN:      Status
    282  *
    283  * DESCRIPTION: Entry point to compile one data table
    284  *
    285  *****************************************************************************/
    286 
    287 static ACPI_STATUS
    288 DtCompileDataTable (
    289     DT_FIELD                **FieldList)
    290 {
    291     const ACPI_DMTABLE_DATA *TableData;
    292     DT_SUBTABLE             *Subtable;
    293     char                    *Signature;
    294     ACPI_TABLE_HEADER       *AcpiTableHeader;
    295     ACPI_STATUS             Status;
    296     DT_FIELD                *RootField = *FieldList;
    297 
    298 
    299     /* Verify that we at least have a table signature and save it */
    300 
    301     Signature = DtGetFieldValue (*FieldList);
    302     if (!Signature)
    303     {
    304         sprintf (AslGbl_MsgBuffer, "Expected \"%s\"", "Signature");
    305         DtNameError (ASL_ERROR, ASL_MSG_INVALID_FIELD_NAME,
    306             *FieldList, AslGbl_MsgBuffer);
    307         return (AE_ERROR);
    308     }
    309 
    310     AslGbl_Signature = UtLocalCacheCalloc (strlen (Signature) + 1);
    311     strcpy (AslGbl_Signature, Signature);
    312 
    313     /*
    314      * Handle tables that don't use the common ACPI table header structure.
    315      * Currently, these are the FACS and RSDP. Also check for an OEMx table,
    316      * these tables have user-defined contents.
    317      */
    318     if (ACPI_COMPARE_NAMESEG (Signature, ACPI_SIG_FACS))
    319     {
    320         Status = DtCompileFacs (FieldList);
    321         if (ACPI_FAILURE (Status))
    322         {
    323             return (Status);
    324         }
    325 
    326         DtSetTableLength ();
    327         return (Status);
    328     }
    329     else if (ACPI_VALIDATE_RSDP_SIG (Signature))
    330     {
    331         Status = DtCompileRsdp (FieldList);
    332         return (Status);
    333     }
    334     else if (ACPI_COMPARE_NAMESEG (Signature, ACPI_SIG_S3PT))
    335     {
    336         Status = DtCompileS3pt (FieldList);
    337         if (ACPI_FAILURE (Status))
    338         {
    339             return (Status);
    340         }
    341 
    342         DtSetTableLength ();
    343         return (Status);
    344     }
    345 
    346     /*
    347      * All other tables must use the common ACPI table header. Insert the
    348      * current iASL IDs (name, version), and compile the header now.
    349      */
    350     DtInsertCompilerIds (*FieldList);
    351 
    352     Status = DtCompileTable (FieldList, AcpiDmTableInfoHeader,
    353         &AslGbl_RootTable);
    354     if (ACPI_FAILURE (Status))
    355     {
    356         return (Status);
    357     }
    358 
    359     DtPushSubtable (AslGbl_RootTable);
    360 
    361     /* Validate the signature via the ACPI table list */
    362 
    363     TableData = AcpiDmGetTableData (Signature);
    364     if (!TableData || AslGbl_CompileGeneric)
    365     {
    366         /* Unknown table signature and/or force generic compile */
    367 
    368         DtCompileGeneric ((void **) FieldList, NULL, NULL);
    369         goto FinishHeader;
    370     }
    371 
    372     /* Dispatch to per-table compile */
    373 
    374     if (TableData->CmTableHandler)
    375     {
    376         /* Complex table, has a handler */
    377 
    378         Status = TableData->CmTableHandler ((void **) FieldList);
    379         if (ACPI_FAILURE (Status))
    380         {
    381             return (Status);
    382         }
    383     }
    384     else if (TableData->TableInfo)
    385     {
    386         /* Simple table, just walk the info table, unless its empty */
    387 
    388         if (FieldList && *FieldList)
    389         {
    390             Subtable = NULL;
    391             Status = DtCompileTable (FieldList, TableData->TableInfo,
    392                 &Subtable);
    393             if (ACPI_FAILURE (Status))
    394             {
    395                 return (Status);
    396             }
    397 
    398             DtInsertSubtable (AslGbl_RootTable, Subtable);
    399             DtPopSubtable ();
    400         }
    401     }
    402     else
    403     {
    404         DtFatal (ASL_MSG_COMPILER_INTERNAL, *FieldList,
    405             "Missing table dispatch info");
    406         return (AE_ERROR);
    407     }
    408 
    409 FinishHeader:
    410 
    411     /* Set the final table length and then the checksum */
    412 
    413     DtSetTableLength ();
    414     AcpiTableHeader = ACPI_CAST_PTR (
    415         ACPI_TABLE_HEADER, AslGbl_RootTable->Buffer);
    416     DtSetTableChecksum (&AcpiTableHeader->Checksum);
    417 
    418     DtDumpFieldList (RootField);
    419     DtDumpSubtableList ();
    420     return (AE_OK);
    421 }
    422 
    423 
    424 /******************************************************************************
    425  *
    426  * FUNCTION:    DtCompileTable
    427  *
    428  * PARAMETERS:  Field               - Current field list pointer
    429  *              Info                - Info table for this ACPI table
    430  *              RetSubtable         - Compile result of table
    431  *
    432  * RETURN:      Status
    433  *
    434  * DESCRIPTION: Compile a subtable
    435  *
    436  *****************************************************************************/
    437 
    438 ACPI_STATUS
    439 DtCompileTable (
    440     DT_FIELD                **Field,
    441     ACPI_DMTABLE_INFO       *Info,
    442     DT_SUBTABLE             **RetSubtable)
    443 {
    444     DT_FIELD                *LocalField;
    445     UINT32                  Length;
    446     DT_SUBTABLE             *Subtable;
    447     DT_SUBTABLE             *InlineSubtable = NULL;
    448     UINT32                  FieldLength = 0;
    449     UINT8                   FieldType;
    450     UINT8                   *Buffer;
    451     UINT8                   *FlagBuffer = NULL;
    452     char                    *String;
    453     UINT32                  CurrentFlagByteOffset = 0;
    454     ACPI_STATUS             Status = AE_OK;
    455 
    456 
    457     if (!Field || !Info)
    458     {
    459         return (AE_BAD_PARAMETER);
    460     }
    461     if (!*Field)
    462     {
    463         /*
    464          * The field list is empty, this means that we are out of fields to
    465          * parse. In other words, we are at the end of the table.
    466          */
    467         return (AE_END_OF_TABLE);
    468     }
    469 
    470     /* Ignore optional subtable if name does not match */
    471 
    472     if ((Info->Flags & DT_OPTIONAL) &&
    473         strcmp ((*Field)->Name, Info->Name))
    474     {
    475         *RetSubtable = NULL;
    476         return (AE_OK);
    477     }
    478 
    479     Length = DtGetSubtableLength (*Field, Info);
    480     if (Length == ASL_EOF)
    481     {
    482         return (AE_ERROR);
    483     }
    484 
    485     Subtable = UtSubtableCacheCalloc ();
    486 
    487     if (Length > 0)
    488     {
    489         String = UtLocalCacheCalloc (Length);
    490         Subtable->Buffer = ACPI_CAST_PTR (UINT8, String);
    491     }
    492 
    493     Subtable->Length = Length;
    494     Subtable->TotalLength = Length;
    495     Buffer = Subtable->Buffer;
    496 
    497     LocalField = *Field;
    498     Subtable->Name = LocalField->Name;
    499 
    500     /*
    501      * Main loop walks the info table for this ACPI table or subtable
    502      */
    503     for (; Info->Name; Info++)
    504     {
    505         if (Info->Opcode == ACPI_DMT_EXTRA_TEXT)
    506         {
    507             continue;
    508         }
    509 
    510         if (!LocalField)
    511         {
    512             sprintf (AslGbl_MsgBuffer, "Found NULL field - Field name \"%s\" needed",
    513                 Info->Name);
    514             DtFatal (ASL_MSG_COMPILER_INTERNAL, NULL, AslGbl_MsgBuffer);
    515             Status = AE_BAD_DATA;
    516             goto Error;
    517         }
    518 
    519         /* Maintain table offsets */
    520 
    521         LocalField->TableOffset = AslGbl_CurrentTableOffset;
    522         FieldLength = DtGetFieldLength (LocalField, Info);
    523         AslGbl_CurrentTableOffset += FieldLength;
    524 
    525         FieldType = DtGetFieldType (Info);
    526         AslGbl_InputFieldCount++;
    527 
    528         if (FieldType != DT_FIELD_TYPE_INLINE_SUBTABLE &&
    529             strcmp (Info->Name, LocalField->Name))
    530         {
    531             sprintf (AslGbl_MsgBuffer, "found \"%s\" expected \"%s\"",
    532                 LocalField->Name, Info->Name);
    533             DtError (ASL_ERROR, ASL_MSG_INVALID_LABEL, LocalField, AslGbl_MsgBuffer);
    534         }
    535 
    536         switch (FieldType)
    537         {
    538         case DT_FIELD_TYPE_FLAGS_INTEGER:
    539             /*
    540              * Start of the definition of a flags field.
    541              * This master flags integer starts at value zero, in preparation
    542              * to compile and insert the flag fields from the individual bits
    543              */
    544             LocalField = LocalField->Next;
    545             *Field = LocalField;
    546 
    547             FlagBuffer = Buffer;
    548             CurrentFlagByteOffset = Info->Offset;
    549             break;
    550 
    551         case DT_FIELD_TYPE_FLAG:
    552 
    553             /* Individual Flag field, can be multiple bits */
    554 
    555             if (FlagBuffer)
    556             {
    557                 /*
    558                  * We must increment the FlagBuffer when we have crossed
    559                  * into the next flags byte within the flags field
    560                  * of type DT_FIELD_TYPE_FLAGS_INTEGER.
    561                  */
    562                 FlagBuffer += (Info->Offset - CurrentFlagByteOffset);
    563                 CurrentFlagByteOffset = Info->Offset;
    564 
    565                 DtCompileFlag (FlagBuffer, LocalField, Info);
    566             }
    567             else
    568             {
    569                 /* TBD - this is an internal error */
    570             }
    571 
    572             LocalField = LocalField->Next;
    573             *Field = LocalField;
    574             break;
    575 
    576         case DT_FIELD_TYPE_INLINE_SUBTABLE:
    577             /*
    578              * Recursion (one level max): compile GAS (Generic Address)
    579              * or Notify in-line subtable
    580              */
    581             *Field = LocalField;
    582 
    583             switch (Info->Opcode)
    584             {
    585             case ACPI_DMT_GAS:
    586 
    587                 Status = DtCompileTable (Field, AcpiDmTableInfoGas,
    588                     &InlineSubtable);
    589                 break;
    590 
    591             case ACPI_DMT_HESTNTFY:
    592 
    593                 Status = DtCompileTable (Field, AcpiDmTableInfoHestNotify,
    594                     &InlineSubtable);
    595                 break;
    596 
    597             case ACPI_DMT_IORTMEM:
    598 
    599                 Status = DtCompileTable (Field, AcpiDmTableInfoIortAcc,
    600                     &InlineSubtable);
    601                 break;
    602 
    603             default:
    604                 sprintf (AslGbl_MsgBuffer, "Invalid DMT opcode: 0x%.2X",
    605                     Info->Opcode);
    606                 DtFatal (ASL_MSG_COMPILER_INTERNAL, NULL, AslGbl_MsgBuffer);
    607                 Status = AE_BAD_DATA;
    608                 break;
    609             }
    610 
    611             if (ACPI_FAILURE (Status))
    612             {
    613                 goto Error;
    614             }
    615 
    616             DtSetSubtableLength (InlineSubtable);
    617 
    618             memcpy (Buffer, InlineSubtable->Buffer, FieldLength);
    619             LocalField = *Field;
    620             break;
    621 
    622         case DT_FIELD_TYPE_LABEL:
    623 
    624             DtWriteFieldToListing (Buffer, LocalField, 0);
    625             LocalField = LocalField->Next;
    626             break;
    627 
    628         default:
    629 
    630             /* Normal case for most field types (Integer, String, etc.) */
    631 
    632             DtCompileOneField (Buffer, LocalField,
    633                 FieldLength, FieldType, Info->Flags);
    634 
    635             DtWriteFieldToListing (Buffer, LocalField, FieldLength);
    636             LocalField = LocalField->Next;
    637 
    638             if (Info->Flags & DT_LENGTH)
    639             {
    640                 /* Field is an Integer that will contain a subtable length */
    641 
    642                 Subtable->LengthField = Buffer;
    643                 Subtable->SizeOfLengthField = FieldLength;
    644             }
    645             break;
    646         }
    647 
    648         Buffer += FieldLength;
    649     }
    650 
    651     *Field = LocalField;
    652     *RetSubtable = Subtable;
    653     return (AE_OK);
    654 
    655 Error:
    656     ACPI_FREE (Subtable->Buffer);
    657     ACPI_FREE (Subtable);
    658     return (Status);
    659 }
    660 
    661 
    662 /******************************************************************************
    663  *
    664  * FUNCTION:    DtCompileTwoSubtables
    665  *
    666  * PARAMETERS:  List                - Current field list pointer
    667  *              TableInfo1          - Info table 1
    668  *              TableInfo1          - Info table 2
    669  *
    670  * RETURN:      Status
    671  *
    672  * DESCRIPTION: Compile tables with a header and one or more same subtables.
    673  *              Include CPEP, EINJ, ERST, MCFG, MSCT, WDAT
    674  *
    675  *****************************************************************************/
    676 
    677 ACPI_STATUS
    678 DtCompileTwoSubtables (
    679     void                    **List,
    680     ACPI_DMTABLE_INFO       *TableInfo1,
    681     ACPI_DMTABLE_INFO       *TableInfo2)
    682 {
    683     ACPI_STATUS             Status;
    684     DT_SUBTABLE             *Subtable;
    685     DT_SUBTABLE             *ParentTable;
    686     DT_FIELD                **PFieldList = (DT_FIELD **) List;
    687 
    688 
    689     Status = DtCompileTable (PFieldList, TableInfo1, &Subtable);
    690     if (ACPI_FAILURE (Status))
    691     {
    692         return (Status);
    693     }
    694 
    695     ParentTable = DtPeekSubtable ();
    696     DtInsertSubtable (ParentTable, Subtable);
    697 
    698     while (*PFieldList)
    699     {
    700         Status = DtCompileTable (PFieldList, TableInfo2, &Subtable);
    701         if (ACPI_FAILURE (Status))
    702         {
    703             return (Status);
    704         }
    705 
    706         DtInsertSubtable (ParentTable, Subtable);
    707     }
    708 
    709     return (AE_OK);
    710 }
    711 
    712 
    713 /******************************************************************************
    714  *
    715  * FUNCTION:    DtCompilePadding
    716  *
    717  * PARAMETERS:  Length              - Padding field size
    718  *              RetSubtable         - Compile result of table
    719  *
    720  * RETURN:      Status
    721  *
    722  * DESCRIPTION: Compile a subtable for padding purpose
    723  *
    724  *****************************************************************************/
    725 
    726 ACPI_STATUS
    727 DtCompilePadding (
    728     UINT32                  Length,
    729     DT_SUBTABLE             **RetSubtable)
    730 {
    731     DT_SUBTABLE             *Subtable;
    732     /* UINT8                   *Buffer; */
    733     char                    *String;
    734 
    735 
    736     Subtable = UtSubtableCacheCalloc ();
    737 
    738     if (Length > 0)
    739     {
    740         String = UtLocalCacheCalloc (Length);
    741         Subtable->Buffer = ACPI_CAST_PTR (UINT8, String);
    742     }
    743 
    744     Subtable->Length = Length;
    745     Subtable->TotalLength = Length;
    746     /* Buffer = Subtable->Buffer; */
    747 
    748     *RetSubtable = Subtable;
    749     return (AE_OK);
    750 }
    751