213 lines · plain
1=======================2ARM Linux 2.6 and upper3=======================4 5 Please check <ftp://ftp.arm.linux.org.uk/pub/armlinux> for6 updates.7 8Compilation of kernel9---------------------10 11 In order to compile ARM Linux, you will need a compiler capable of12 generating ARM ELF code with GNU extensions. GCC 3.3 is known to be13 a good compiler. Fortunately, you needn't guess. The kernel will report14 an error if your compiler is a recognized offender.15 16 To build ARM Linux natively, you shouldn't have to alter the ARCH = line17 in the top level Makefile. However, if you don't have the ARM Linux ELF18 tools installed as default, then you should change the CROSS_COMPILE19 line as detailed below.20 21 If you wish to cross-compile, then alter the following lines in the top22 level make file::23 24 ARCH = <whatever>25 26 with::27 28 ARCH = arm29 30 and::31 32 CROSS_COMPILE=33 34 to::35 36 CROSS_COMPILE=<your-path-to-your-compiler-without-gcc>37 38 eg.::39 40 CROSS_COMPILE=arm-linux-41 42 Do a 'make config', followed by 'make Image' to build the kernel43 (arch/arm/boot/Image). A compressed image can be built by doing a44 'make zImage' instead of 'make Image'.45 46 47Bug reports etc48---------------49 50 Please send patches to the patch system. For more information, see51 http://www.arm.linux.org.uk/developer/patches/info.php Always include some52 explanation as to what the patch does and why it is needed.53 54 Bug reports should be sent to linux-arm-kernel@lists.arm.linux.org.uk,55 or submitted through the web form at56 http://www.arm.linux.org.uk/developer/57 58 When sending bug reports, please ensure that they contain all relevant59 information, eg. the kernel messages that were printed before/during60 the problem, what you were doing, etc.61 62 63Include files64-------------65 66 Several new include directories have been created under include/asm-arm,67 which are there to reduce the clutter in the top-level directory. These68 directories, and their purpose is listed below:69 70 ============= ==========================================================71 `arch-*` machine/platform specific header files72 `hardware` driver-internal ARM specific data structures/definitions73 `mach` descriptions of generic ARM to specific machine interfaces74 `proc-*` processor dependent header files (currently only two75 categories)76 ============= ==========================================================77 78 79Machine/Platform support80------------------------81 82 The ARM tree contains support for a lot of different machine types. To83 continue supporting these differences, it has become necessary to split84 machine-specific parts by directory. For this, the machine category is85 used to select which directories and files get included (we will use86 $(MACHINE) to refer to the category)87 88 To this end, we now have arch/arm/mach-$(MACHINE) directories which are89 designed to house the non-driver files for a particular machine (eg, PCI,90 memory management, architecture definitions etc). For all future91 machines, there should be a corresponding arch/arm/mach-$(MACHINE)/include/mach92 directory.93 94 95Modules96-------97 98 Although modularisation is supported (and required for the FP emulator),99 each module on an ARM2/ARM250/ARM3 machine when is loaded will take100 memory up to the next 32k boundary due to the size of the pages.101 Therefore, is modularisation on these machines really worth it?102 103 However, ARM6 and up machines allow modules to take multiples of 4k, and104 as such Acorn RiscPCs and other architectures using these processors can105 make good use of modularisation.106 107 108ADFS Image files109----------------110 111 You can access image files on your ADFS partitions by mounting the ADFS112 partition, and then using the loopback device driver. You must have113 losetup installed.114 115 Please note that the PCEmulator DOS partitions have a partition table at116 the start, and as such, you will have to give '-o offset' to losetup.117 118 119Request to developers120---------------------121 122 When writing device drivers which include a separate assembler file, please123 include it in with the C file, and not the arch/arm/lib directory. This124 allows the driver to be compiled as a loadable module without requiring125 half the code to be compiled into the kernel image.126 127 In general, try to avoid using assembler unless it is really necessary. It128 makes drivers far less easy to port to other hardware.129 130 131ST506 hard drives132-----------------133 134 The ST506 hard drive controllers seem to be working fine (if a little135 slowly). At the moment they will only work off the controllers on an136 A4x0's motherboard, but for it to work off a Podule just requires137 someone with a podule to add the addresses for the IRQ mask and the138 HDC base to the source.139 140 As of 31/3/96 it works with two drives (you should get the ADFS141 `*configure` harddrive set to 2). I've got an internal 20MB and a great142 big external 5.25" FH 64MB drive (who could ever want more :-) ).143 144 I've just got 240K/s off it (a dd with bs=128k); that's about half of what145 RiscOS gets; but it's a heck of a lot better than the 50K/s I was getting146 last week :-)147 148 Known bug: Drive data errors can cause a hang; including cases where149 the controller has fixed the error using ECC. (Possibly ONLY150 in that case...hmm).151 152 1531772 Floppy154-----------155 This also seems to work OK, but hasn't been stressed much lately. It156 hasn't got any code for disc change detection in there at the moment which157 could be a bit of a problem! Suggestions on the correct way to do this158 are welcome.159 160 161`CONFIG_MACH_` and `CONFIG_ARCH_`162---------------------------------163 A change was made in 2003 to the macro names for new machines.164 Historically, `CONFIG_ARCH_` was used for the bonafide architecture,165 e.g. SA1100, as well as implementations of the architecture,166 e.g. Assabet. It was decided to change the implementation macros167 to read `CONFIG_MACH_` for clarity. Moreover, a retroactive fixup has168 not been made because it would complicate patching.169 170 Previous registrations may be found online.171 172 <http://www.arm.linux.org.uk/developer/machines/>173 174Kernel entry (head.S)175---------------------176 The initial entry into the kernel is via head.S, which uses machine177 independent code. The machine is selected by the value of 'r1' on178 entry, which must be kept unique.179 180 Due to the large number of machines which the ARM port of Linux provides181 for, we have a method to manage this which ensures that we don't end up182 duplicating large amounts of code.183 184 We group machine (or platform) support code into machine classes. A185 class typically based around one or more system on a chip devices, and186 acts as a natural container around the actual implementations. These187 classes are given directories - arch/arm/mach-<class> - which contain188 the source files and include/mach/ to support the machine class.189 190 For example, the SA1100 class is based upon the SA1100 and SA1110 SoC191 devices, and contains the code to support the way the on-board and off-192 board devices are used, or the device is setup, and provides that193 machine specific "personality."194 195 For platforms that support device tree (DT), the machine selection is196 controlled at runtime by passing the device tree blob to the kernel. At197 compile-time, support for the machine type must be selected. This allows for198 a single multiplatform kernel build to be used for several machine types.199 200 For platforms that do not use device tree, this machine selection is201 controlled by the machine type ID, which acts both as a run-time and a202 compile-time code selection method. You can register a new machine via the203 web site at:204 205 <http://www.arm.linux.org.uk/developer/machines/>206 207 Note: Please do not register a machine type for DT-only platforms. If your208 platform is DT-only, you do not need a registered machine type.209 210---211 212Russell King (15/03/2004)213