cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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Build.txt (4269B)

      1Build Framework
      2===============
      3
      4The perf build framework was adopted from the kernel build system, hence the
      5idea and the way how objects are built is the same.
      6
      7Basically the user provides set of 'Build' files that list objects and
      8directories to nest for specific target to be build.
      9
     10Unlike the kernel we don't have a single build object 'obj-y' list that where
     11we setup source objects, but we support more. This allows one 'Build' file to
     12carry a sources list for multiple build objects.
     13
     14
     15Build framework makefiles
     16-------------------------
     17
     18The build framework consists of 2 Makefiles:
     19
     20  Build.include
     21  Makefile.build
     22
     23While the 'Build.include' file contains just some generic definitions, the
     24'Makefile.build' file is the makefile used from the outside. It's
     25interface/usage is following:
     26
     27  $ make -f tools/build/Makefile.build srctree=$(KSRC) dir=$(DIR) obj=$(OBJECT)
     28
     29where:
     30
     31  KSRC   - is the path to kernel sources
     32  DIR    - is the path to the project to be built
     33  OBJECT - is the name of the build object
     34
     35When succefully finished the $(DIR) directory contains the final object file
     36called $(OBJECT)-in.o:
     37
     38  $ ls $(DIR)/$(OBJECT)-in.o
     39
     40which includes all compiled sources described in 'Build' makefiles.
     41
     42
     43Build makefiles
     44---------------
     45
     46The user supplies 'Build' makefiles that contains a objects list, and connects
     47the build to nested directories.
     48
     49Assume we have the following project structure:
     50
     51  ex/a.c
     52    /b.c
     53    /c.c
     54    /d.c
     55    /arch/e.c
     56    /arch/f.c
     57
     58Out of which you build the 'ex' binary ' and the 'libex.a' library:
     59
     60  'ex'      - consists of 'a.o', 'b.o' and libex.a
     61  'libex.a' - consists of 'c.o', 'd.o', 'e.o' and 'f.o'
     62
     63The build framework does not create the 'ex' and 'libex.a' binaries for you, it
     64only prepares proper objects to be compiled and grouped together.
     65
     66To follow the above example, the user provides following 'Build' files:
     67
     68  ex/Build:
     69    ex-y += a.o
     70    ex-y += b.o
     71    ex-y += b.o # duplicates in the lists are allowed
     72
     73    libex-y += c.o
     74    libex-y += d.o
     75    libex-y += arch/
     76
     77  ex/arch/Build:
     78    libex-y += e.o
     79    libex-y += f.o
     80
     81and runs:
     82
     83  $ make -f tools/build/Makefile.build dir=. obj=ex
     84  $ make -f tools/build/Makefile.build dir=. obj=libex
     85
     86which creates the following objects:
     87
     88  ex/ex-in.o
     89  ex/libex-in.o
     90
     91that contain request objects names in Build files.
     92
     93It's only a matter of 2 single commands to create the final binaries:
     94
     95  $ ar  rcs libex.a libex-in.o
     96  $ gcc -o ex ex-in.o libex.a
     97
     98You can check the 'ex' example in 'tools/build/tests/ex' for more details.
     99
    100
    101Makefile.include
    102----------------
    103
    104The tools/build/Makefile.include makefile could be included
    105via user makefiles to get usefull definitions.
    106
    107It defines following interface:
    108
    109  - build macro definition:
    110      build := -f $(srctree)/tools/build/Makefile.build dir=. obj
    111
    112    to make it easier to invoke build like:
    113      make $(build)=ex
    114
    115
    116Fixdep
    117------
    118It is necessary to build the fixdep helper before invoking the build.
    119The Makefile.include file adds the fixdep target, that could be
    120invoked by the user.
    121
    122
    123Rules
    124-----
    125
    126The build framework provides standard compilation rules to handle .S and .c
    127compilation.
    128
    129It's possible to include special rule if needed (like we do for flex or bison
    130code generation).
    131
    132
    133CFLAGS
    134------
    135
    136It's possible to alter the standard object C flags in the following way:
    137
    138  CFLAGS_perf.o        += '...'  - adds CFLAGS for perf.o object
    139  CFLAGS_gtk           += '...'  - adds CFLAGS for gtk build object
    140  CFLAGS_REMOVE_perf.o += '...'  - removes CFLAGS for perf.o object
    141  CFLAGS_REMOVE_gtk    += '...'  - removes CFLAGS for gtk build object
    142
    143This C flags changes has the scope of the Build makefile they are defined in.
    144
    145
    146Dependencies
    147------------
    148
    149For each built object file 'a.o' the '.a.cmd' is created and holds:
    150
    151  - Command line used to built that object
    152    (for each object)
    153
    154  - Dependency rules generated by 'gcc -Wp,-MD,...'
    155    (for compiled object)
    156
    157All existing '.cmd' files are included in the Build process to follow properly
    158the dependencies and trigger a rebuild when necessary.
    159
    160
    161Single rules
    162------------
    163
    164It's possible to build single object file by choice, like:
    165
    166  $ make util/map.o    # objects
    167  $ make util/map.i    # preprocessor
    168  $ make util/map.s    # assembly