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| howtos:hardware:arm:gcc-11.x_aarch64_cross-compiler [2021/09/25 15:10 (UTC)] – [Aarch64 cross-compiling 'HOWTO' example] updated code exaga | howtos:hardware:arm:gcc-11.x_aarch64_cross-compiler [2021/10/01 09:25 (UTC)] – [AArch64 cross-compiling 'HOWTO' example] removed superfluous text exaga |
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| As a pre-requisite, you should have; | As a pre-requisite, you should have; |
| * a Raspberry Pi 3 or 4 (i.e. a 64bit CPU) running Slackware ARM current with as much unused [>= 5GB] storage space on your system as possible. \\ | * a Raspberry Pi 3 or 4 (i.e. a 64-bit CPU) running Slackware ARM current with as much unused [>= 5GB] storage space on your system as possible. \\ |
| * [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/a/|gawk]], [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|git]], [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|bison]] and [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|flex]], already installed on your system. \\ | * [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/a/|gawk]], [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|git]], [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|bison]] and [[http://ftp.arm.slackware.com/slackwarearm/slackwarearm-current/slackware/d/|flex]], already installed on your system. \\ |
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| ===== Aarch64 cross-compiler script code ===== | ===== AArch64 cross-compiler script code ===== |
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| Download the 'SARPi64.SlackBuild-gcc-11.2.0-aarch64-cc.sh' file by clicking the link at the top of the script code (or copy and paste the code if you prefer) below. | Download the 'SARPi64.SlackBuild-gcc-11.2.0-aarch64-cc.sh' file by clicking the link at the top of the script code (or copy and paste the code if you prefer) below. |
| </file> | </file> |
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| ===== Configuring the system to use the Aarch64 cross-compiler ===== | ===== Configuring the system to use the AArch64 cross-compiler ===== |
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| Once the cross-compiler has been built and you intend to use it to compile Aarch64 [64bit] binaries, the location of the tool-chains must be exported to your system's $PATH variable. It's also prudent to have this entry appear before all other PATHs. So, for example, to check what your existing $PATH includes, use the 'echo $PATH' command like this: | Once the cross-compiler has been built and you intend to use it to compile AArch64 [64-bit] binaries, the location of the tool-chains must be exported to your system's $PATH variable. It's also prudent to have this entry appear before all other PATHs. So, for example, to check what your existing $PATH includes, use the 'echo $PATH' command like this: |
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| <code>root@slackware:~# echo $PATH | <code>root@slackware:~# echo $PATH |
| The example output above all looks good because the cross compile PATH appears first before everything else. | The example output above all looks good because the cross compile PATH appears first before everything else. |
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| ===== Aarch64 cross-compiling 'HOWTO' example ===== | ===== AArch64 cross-compiling 'HOWTO' example ===== |
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| So, when the Aarch64 tool-chains feature in the $PATH on the system, they can be utilised to build software for the ARMv8 architecture instead of your Slackware ARM system's [ARMv7] existing infrastructure. It's all done via the 'make' process. | So, when the AArch64 tool-chains feature in the $PATH on the system, they can be utilised to build software for the ARMv8 architecture instead of your Slackware ARM system's [ARMv7] existing infrastructure. It's all done via the 'make' process. |
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| As an example to show how this can be achieved, the bespoke RPi kernel source 'master' branch will be used. This kernel source will be downloaded and located in '/tmp/linux-rpi' directory. [**NB: note that this is __NOT__ '/usr/src/linux' - it should never reside in that standard location for cross-compiling purposes!**]. After downloading the Linux source, use 'cd' to the directory where it's located: | As an example to show how this can be achieved, the bespoke RPi kernel source 'master' branch will be used. This kernel source will be downloaded and located in '/tmp/linux-rpi' directory. [**NB: note that this is __NOT__ '/usr/src/linux' - it should never reside in that standard location for cross-compiling purposes!**]. After downloading the Linux source, use 'cd' to the directory where it's located: |
| What's missing now is a kernel '.config' - a file that includes instructions (i.e. settings) that's an essential prerequisite in order to compile the Linux source into a resulting kernel image file - and you won't be doing much without creating one first. This is __much__ easier said than done if you're starting from scratch, because it requires intimate knowledge about the the computer/device hardware that you're building the kernel to support. However, with the Raspberry Pis (and many other ARM devices) there is such a thing as a 'default config', or 'defconfig', that can be called to build the kernel '.config' file for you and save a lot of time and effort (and unfortunately a huge amount of education and experience is also wasted in this process). So in the interest of saving time, let's do it the easy and lazy way for this example... | What's missing now is a kernel '.config' - a file that includes instructions (i.e. settings) that's an essential prerequisite in order to compile the Linux source into a resulting kernel image file - and you won't be doing much without creating one first. This is __much__ easier said than done if you're starting from scratch, because it requires intimate knowledge about the the computer/device hardware that you're building the kernel to support. However, with the Raspberry Pis (and many other ARM devices) there is such a thing as a 'default config', or 'defconfig', that can be called to build the kernel '.config' file for you and save a lot of time and effort (and unfortunately a huge amount of education and experience is also wasted in this process). So in the interest of saving time, let's do it the easy and lazy way for this example... |
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| For the Raspberry Pi 3 to build a default kernel '.config' file for Aarch64 architecture: | For the Raspberry Pi 3 to build a default kernel '.config' file for AArch64 architecture: |
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| <code>root@slackware:/tmp/linux-rpi# make ARCH=arm64 CROSS_COMPILE=aarch64-linux- bcm2709_defconfig </code> | <code>root@slackware:/tmp/linux-rpi# make ARCH=arm64 CROSS_COMPILE=aarch64-linux- bcm2709_defconfig </code> |
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| For the Raspberry Pi 4 to build a default kernel '.config' file for Aarch64 architecture: | For the Raspberry Pi 4 to build a default kernel '.config' file for AArch64 architecture: |
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| <code>root@slackware:/tmp/linux-rpi# make ARCH=arm64 CROSS_COMPILE=aarch64-linux- bcm2711_defconfig </code> | <code>root@slackware:/tmp/linux-rpi# make ARCH=arm64 CROSS_COMPILE=aarch64-linux- bcm2711_defconfig </code> |
| <note warning>**BEFORE CONTINUING - Make a back-up __FIRST__ of your '/boot/' directory before coping any new files to it, in case things don't go exactly as planned. Only reboot once everything is correctly in place and you have your backup(s) to fall-back on.**</note> | <note warning>**BEFORE CONTINUING - Make a back-up __FIRST__ of your '/boot/' directory before coping any new files to it, in case things don't go exactly as planned. Only reboot once everything is correctly in place and you have your backup(s) to fall-back on.**</note> |
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| So with everything compiled and built, you just need to copy the 'kernel' image, 'DTBs' and 'System.map' to your '/boot' directory. Replace KERNEL_IMAGE with the correct filename of the kernel for your Raspberry Pi device: | So with everything compiled and built, you just need to copy the 'kernel' image, 'DTBs' and 'System.map' to your '/boot' directory. |
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| <note important>NB: For the RPi3 the kernel image is named 'kernel7.img' and for the RPi4 the kernel image is named 'kernel7l.img'. This filename __MUST__ be correct in order for the boot-loader to run the kernel! If you have specified a custom kernel image filename in the '/boot/config.txt' file then you already know what you're doing. ;-)</note> | <note important>NB: By default, on Raspberry Pi ARMv7 [32-bit] systems, the kernel image is named 'kernel7.img' on the RPi3, and for the RPi4 the kernel image is named 'kernel7l.img' - where the "L" is actually an indicator for "Large Physical Address Extension (LPAE)". However, on Raspberry Pi ARMv8 [64-bit] systems the kernel is named 'kernel8.img'. This filename __MUST__ be correct in order for the boot-loader to find and run the ARMv8 [64-bit] kernel! If you have specified a custom kernel image filename in the '/boot/config.txt' file then you already know what you're doing here. ;-)</note> |
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| <code>root@slackware:/tmp/linux-rpi# cp -avr arch/arm64/boot/Image /boot/KERNEL_IMAGE" | <code>root@slackware:/tmp/linux-rpi# cp -avr arch/arm64/boot/Image /boot/kernel8.img" |
| root@slackware:/tmp/linux-rpi# cp -avr arch/arm64/boot/dts/broadcom/bcm27*.dtb /boot/ | root@slackware:/tmp/linux-rpi# cp -avr arch/arm64/boot/dts/broadcom/bcm27*.dtb /boot/ |
| root@slackware:/tmp/linux-rpi# cp -avr System.map /boot/System.map</code> | root@slackware:/tmp/linux-rpi# cp -avr System.map /boot/System.map</code> |
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| That's it! When you reboot your system it should now be using a 64bit kernel and modules. One should be mindful that [[http://arm.slackware.com/|Slackware Aarch64]] is in development and building kernels using a cross-compiler will soon become superfluous on that system architecture, but for 32bit systems and users a cross-compiler may still be relevant. | That's it! When you reboot your system it should now be using a 64-bit kernel and modules. One should be mindful that [[http://arm.slackware.com/|Slackware AArch64]] is in development and building kernels using a cross-compiler will soon become superfluous on that system architecture, but for 32-bit systems and users a cross-compiler may still be relevant. |
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| I hope this Aarch64 cross-compiler build script and/or information will be useful for Slackware [ARM] users in whatever ways are possible. Any questions or assistance can be addressed via the [[https://www.linuxquestions.org/questions/slackware-arm-108/|Linux Questions forum(s)]] | I hope this AArch64 cross-compiler build script and/or information will be useful for Slackware [ARM] users in whatever ways are possible. Any questions or assistance can be addressed via the [[https://www.linuxquestions.org/questions/slackware-arm-108/|Linux Questions forum(s)]] |
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| Thanks very much for your interest in this Aarch64 cross-compiler on the Raspberry Pi. | Thanks very much for your interest in this AArch64 cross-compiler on the Raspberry Pi. |
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| ====== Sources ====== | ====== Sources ====== |
| <!-- You must remove the tag-word "template" below before saving your new page --> | <!-- You must remove the tag-word "template" below before saving your new page --> |
| {{tag>howtos slackware raspberry pi arm aarch64 arm64 armv8 cross-compile author_exaga}} | {{tag>howtos slackware raspberry pi arm aarch64 arm64 armv8 cross-compile author_exaga}} |
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