resources: Add doc for riscv-fs-busybox-opensbi-nodisk resource #61
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Inspired by riscv-fs-nodisk however, replacing legacy Berkeley bootloader (bbl) with OpenSBI FW_PAYLOAD bootloader, additionally just using default Linux and Busybox configurations instead of not up-to-date UCanLinux configs.
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@powerjg or @BobbyRBruce i would like to add you as reviewers, but i am not sure, if i am authorized. |
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First, thanks for the contribution! I think this information is great to get out to the broader community.
However, I'm not sure the appropriate place is gem5-resources. This repo is for the sources to build resources that are available on resources.gem5.org. Are you proposing that we (the gem5 community) distribute this kernel/bootloader/filesystem? If so, who are the users of this?
Maybe a better place for this document would be the gem5 blog: https://www.gem5.org/blog/
I'm open to a conversation, though :)
One last thing, if you could run a markdown linter, it would improve the formatting. E.g., https://github.com/markdownlint/markdownlint or https://marketplace.visualstudio.com/items?itemName=DavidAnson.vscode-markdownlint if you're using vscode.
| [GNU toolchain for RISC-V](https://github.com/riscv-collab/riscv-gnu-toolchain). | ||
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| This step is necessary if you do not have basic libraries built for RISCV or | ||
| if you're cross-compiling RISCV. | ||
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| ```sh | ||
| cd riscv-all-in-one/ | ||
| git clone https://github.com/riscv-collab/riscv-gnu-toolchain.git | ||
| cd riscv-gnu-toolchain | ||
| git switch --detach 20f615317e2ce888dfc11b29ccde4a649494b654 # for reproducability, newer versions should work either | ||
| mkdir build | ||
| cd build | ||
| # --prefix parameter specifying the installation location | ||
| # --enable-multilib build either cross-compiler with support for both 32-bit and 64-bit | ||
| ../configure --prefix=/path/to/rvtoolchain --enable-multilib | ||
| make linux -j$(nproc) | ||
| ``` | ||
| To update the PATH environment variable so that the RISCV compilers can be | ||
| found, | ||
| ```sh | ||
| export PATH=/path/to/rvtoolchain/bin/:$PATH | ||
| ``` |
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Do we have to compile the toolchain? If there's a good reason not to use the precompiled toolchain from Ubuntu, then this step is OK, but if it's possible to use the precompiled toolchain, then we should do that.
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It might be helpful if you modify the toolchain itself, however in the default case for this resource the shipped toolchain is faily enough, so i changed it to use Debian's g++-12-riscv64-linux-gnu package. See lines 43-74.
| git clone --branch 1_36_stable https://git.busybox.net/busybox.git # choose a stable branch | ||
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| # alternatively downloading tar | ||
| wget https://git.busybox.net/busybox/snapshot/busybox-1_36_1.tar.bz2 |
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I assume we do have to compile busybox (unlike gcc above). But can you confirm this?
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Yes, Busybox is not distributing for the required RISCV platform (see their download page). Also i configure it to use no shared libraries in order to simplify the guide.
| make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- defconfig | ||
| make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- menuconfig |
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riscv64-unknown-linux-gnu-? Above you used riscv64-linux-gnu-.
We should use just one cross compiler, and, unless there's a really good reason, it should be a precompiled toolchain, not one that we compile ourselves.
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In the initial commit the lines that referred to riscv64-linux-gnu- just mentioned an alternative usage if the toolchain was not prefixed by the default riscv64-unknown-linux-gnu-. Sorry for the confusion.
As i use the Debian shipped compilers now, i have to specify the toolchain prefix for scons anyways. See line 109.
| You can run the created bootloader with Linux and Busybox payload using the example riscv `fs_linux.py` config, | ||
| ```sh | ||
| cd gem5 | ||
| ./build/RISCV/gem5.opt configs/example/riscv/fs_linux.py --kernel="../gem5-resources/src/riscv-fs/riscv-all-in-one/opensbi/build/platform/generic/firmware/fw_payload.elf" |
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I would prefer all examples to use the stdlib. If you could describe how to turn this into a Workload it would improve the description.
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This is the hard part for me. As far as i see, only specifying a bootloader without kernel and disk image is not intended by the boards, e.g. RiscvBoard or RISCVMatchedBoard.
Therefore i just show how to slightly modify the riscv-fs.py by obtaining the new kernel or bootloader resource and leaving the disk_image (and kernel) parameter of the set_kernel_disk_workload call unmodified (as dummy resource). See lines 266-282
In the end it might look like
# Set the Full System workload.
board.set_kernel_disk_workload(
kernel=obtain_resource(
"riscv-bootloader-vmlinux-5.10", resource_version="1.0.0"
), # dummy resource
disk_image=obtain_resource("riscv-disk-img", resource_version="1.0.0"), # dummy resource
bootloader=obtain_resource(
"riscv-fs-busybox-opensbi-nodisk", resource_version="1.0.0"
),
)following suggestion of review on PR gem5#61 to use the more convinient precompiled toolchain. self-compiled is useful for modified toolchain, but not required for reproducibility of the standard resource though
improvements for PR gem5#61 - fix markdown formatting (blank lines, links, etc.) - clarify comment alternative initramfs.cpio archive generation
- change permalink and add a tag to highlight nodisk charakter - reorder tags to align with other resource READMEs - describe how to use the resource within the gem5 stdlib framework as a bootloader or kernel passed to set_kernel_disk_workload() - add licensing notes for OpenSBI, Linux and Busybox
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Thank you very much for the thorough review and the hints for improvement! I should have incorporated your suggestions somehow (see comments on your comments :).
Regarding the appropriate place. So why to distribute via gem5-resources? -- It might be a good starting point for people to check whether this type of "nodisk resource" already fits their needs. |
- move m5 exit to beginning of script and extract shell setup into extra script for better readability - swap setsid,hotplug lines (script doesn't proceed after setsid line) - fix version in busybox docs link
teloecho
changed the title
Inspired by riscv-fs-nodisk however, replacing legacy Berkeley bootloader (bbl) with OpenSBI FW_PAYLOAD bootloader, additionally just using default Linux and Busybox configurations instead of not up-to-date UCanLinux configs.
I was missing an up-to-date guide for fully self-build simple linux environment for Gem5 RISC-V full system simulations.
Therefore i compiled this guide from other guide here and online together.
The use case could be playing around with custom RISC-V instructions and custom toolchain.
Btw: i tried to use pre-commit, but i got the error
No .pre-commit-config.yaml file was foundon commit.