Add LoongArch64 support #46

zhaixiaojuan · 2023-01-18T06:12:51Z

The LoongArch architecture (LoongArch) is an Instruction Set Architecture (ISA) that has a RISC style.

Documentations:
ISA:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html
ABI:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html
More docs can be found at:
https://loongson.github.io/LoongArch-Documentation/README-EN.html

sunfishcode · 2023-02-03T21:53:12Z

It looks like this is failing in CI, with error: unknown target triple 'loongarch64-unknown-linux-gnuf64', please use -triple or -arch; could you take a look?

zhaixiaojuan · 2023-02-06T01:16:45Z

It looks like this is failing in CI, with error: unknown target triple 'loongarch64-unknown-linux-gnuf64', please use -triple or -arch; could you take a look

yes, I'm looking for the reason, thanks

zhaixiaojuan · 2023-02-06T02:27:29Z

The error was caused by the llvm. we should wait for the official support for the loongarch target when llvm16 released

rust-lang/rust#107224

xen0n

We should definitely wait until rust-lang/rust#96971 is merged though.

gen/ioctl/generate.sh

xen0n · 2023-02-09T07:11:21Z

gen/ioctl/generate.sh

@@ -23,6 +23,9 @@ i686-linux-gnu-gcc main.c list.o -o main.exe $cflags
 x86_64-linux-gnu-gcc -Iinclude -c list.c $cflags
 x86_64-linux-gnu-gcc main.c list.o -o main.exe $cflags
 ./main.exe >> "$out"
+loongarch64-unknown-linux-gnu-gcc -Iinclude -c list.c $cflags
+loongarch64-unknown-linux-gnu-gcc main.c list.o -o main.exe $cflags


Which distro this script is supposed to get run on? This looks like the Debian/Ubuntu cross toolchain naming but AFAIK the Debian port still hasn't settled yet?

xen0n · 2023-02-09T07:12:22Z

gen/ioctl/list.c

@@ -95,7 +95,7 @@ struct sockaddr {
 #include <linux/joystick.h>
 #include <linux/kd.h>
 #include <linux/kcov.h>
-#if !defined(__arm__) && !defined(__powerpc64__) && !defined(__riscv) // various errors
+#if !defined(__arm__) && !defined(__loongarch64) && !defined(__powerpc64__) && !defined(__riscv) // various errors


Isn't __loongarch__ enough? Even if you want to restrict to 64-bit LoongArch you should probably use __loongarch_lp64 as the __loongarch64 symbol is deprecated.

thanks for all your advice

xen0n · 2023-03-29T08:42:25Z

Okay, so my Rust porting skills obviously need some refreshing, and this crate is actually blocking Cargo build, so we can't directly jump to Tier-2-with-host-tools in rust-lang/rust#96971. (Tools were basically dep-free from the good ol' days, so rustc and cargo basically always come together IIRC.)

zhaixiaojuan · 2023-03-29T10:10:33Z

@sunfishcode
This ci test fails because llvm14 does not support the loongarch architecture and needs to be upgraded to llvm16 to pass this test. Can you help me upgrade the test environment? thanks

sunfishcode · 2023-03-30T22:11:39Z

I don't know of an easy way to update the test environment; we're already using ubuntu-latest. Would it work for now to disable the tests on loongarch64?

zhaixiaojuan · 2023-03-31T01:03:53Z

I don't know of an easy way to update the test environment; we're already using ubuntu-latest. Would it work for now to disable the tests on loongarch64?

OK. disable the tests on loongarch64 is a good choice at the current test environment

xen0n

Disabling tests for loongarch64 for now is okay for me. We can always do it later once enough infra has been brought up. (We have done quite a lot in the past 2 years, but obviously that's still not "enough".)

xen0n · 2023-03-31T02:48:21Z

gen/ioctl/generate.sh

@@ -44,5 +44,8 @@ qemu-riscv64 -L /usr/riscv64-linux-gnu ./main.exe >> "$out"
 s390x-linux-gnu-gcc -Iinclude -c list.c $cflags
 s390x-linux-gnu-gcc main.c list.o -o main.exe $cflags
 qemu-s390x -L /usr/s390x-linux-gnu ./main.exe >> "$out"
+loongarch64-linux-gnu-gcc -Iinclude -c list.c $cflags
+loongarch64-linux-gnu-gcc main.c list.o -o main.exe $cflags
+./main.exe >> "$out"


Hmm this is implying the host environment can transparently run LoongArch binaries. See how other non-x86 arches launch their artifacts with qemu linux-user emulation.

But, as we don't have Debian/Ubuntu cross toolchains available yet, in fact even loongarch64-linux-gnu-gcc is not supposed to be available. How are we going to deal with this?

qemu linux-user emulation method use the "-L /usr/xxx-linux-gnu",which specifies the library path to be searched by the qemu simulator. This path is usually set by the cross-compilation toolchain installer.
So no matter which method you use, compile the cross tool chain is the first step,
Maybe use the qemu simulator is more complicated, since most os use a lower
qemu version which does not support loongarch yet

Yeah, the key point is: this script would be run by any contributor to this library, and adding those changes as-is would affect anyone not familiar with LoongArch development, which I suppose is the majority. (Also not everyone uses loongarch64-linux-gnu; Gentoo for example uses loongarch64-unknown-linux-gnu, notice the vendor field.)

We may have to disable the part for everyone else for the time being: maybe wrap them in a if false; then ... fi block with some explanations attached.

The vendor in the triple is configured by itself, eg, centos/fedora use x86_64-redhat-linux-gcc, alpine use x86_64-alpine-linux-musl-gcc, so use the common case without unknown

The vendor in the triple is configured by itself, eg, centos/fedora use x86_64-redhat-linux-gcc, alpine use x86_64-alpine-linux-musl-gcc, so use the common case without unknown

I'm not saying that we "should" choose one triple over another, but rather there's simply not a common case right now. Other arches are apparently using Debian cross tuples, but we don't currently have such a cross toolchain package available upstream, so loongarch64-linux-gnu is equally unusable as other variants so far.

(And, the argument that loongarch64-linux-gnu should be chosen because it's the "common denominator" is moot, because the current situation inherently favors Debian/Ubuntu hosts over other distros, and other distros will not work even if they all have the "common" parts in their versions of LoongArch triples. The command names are simply different, period. It's not going to magically match only because the "commonality" is recognized somehow.)

https://wiki.debian.org/Ports/loong64 has publised the loongarch64 target triple "loongarch64-linux-gnu"
So we can use the name as most arches do. yes, We can't get such a cross toolchain directly from the upstream now,
we can compile it. And debian community work is also in progress.

So for now, would it work to just check in pregenerated loongarch64 files as separate files in the repo, and just have this gen/ioctl/generate.sh script just cat them into the output? That way, it doesn't depend on a toolchain that ubuntu-latest users won't have an easy way to install.

Sorry, I don't fully understand what you mean. Do you mean that our current patch only adds these files in the output src directory, or just temporarily removes the part of the gen/ioctl/generate.sh file that uses the loongarch cross-tool chain until the upstream cross-tool chain is available?

@zhaixiaojuan I believe it's just a matter of moving the LoongArch part of the generated output to another file, so we can temporarily avoid calling into the toolchain non-existent on others' systems.

In other words, instead of:

loongarch64-linux-gnu-gcc -Iinclude -c list.c $cflags loongarch64-linux-gnu-gcc main.c list.o -o main.exe $cflags ./main.exe >> "$out"

You should instead do this for the time being:

# cross LoongArch toolchain is not yet packaged in mainstream distros yet, # so pre-generated output is used for the time being cat loongarch-ioctls.txt >> "$out"

zhaixiaojuan · 2023-04-10T01:31:36Z

@sunfishcode Disable tests for loongarch64 is still needed for lower llvm versions. thanks

heiher · 2023-04-12T07:26:38Z

rust-lang/rust#96971 merged. Maybe we are ready to go? :)

xen0n · 2023-04-10T04:25:48Z

gen/ioctl/generate.sh

@@ -44,5 +44,8 @@ qemu-riscv64 -L /usr/riscv64-linux-gnu ./main.exe >> "$out"
 s390x-linux-gnu-gcc -Iinclude -c list.c $cflags
 s390x-linux-gnu-gcc main.c list.o -o main.exe $cflags
 qemu-s390x -L /usr/s390x-linux-gnu ./main.exe >> "$out"
+# As LoongArch cross toolchain is not yet packaged in mainstream distros yet,
+# so pre-generated output is used for the time being


Suggested change

# so pre-generated output is used for the time being

# pre-generated output is used for the time being

xen0n · 2023-04-12T12:39:12Z

gen/src/main.rs

-                    linux_version,
-                );
+                if !pre_gen {
+                    run_bindgen(


Does this mean LoongArch code could potentially get outdated if the bindgen version gets bumped by someone else not aware of this?

Yep, that is indeed a risk of pre-generation. It would be great if we could switch to automatic generation as soon as possible.

heiher · 2023-04-14T14:23:11Z

Hello, @sunfishcode In my recent pushes, I added support for pre-generation to the generator, which enables LoongArch to function in the current CI environment.

I wanted to check with you if there are any additional changes or improvements that you would like me to make before merging the pull request. I understand that you have a lot on your plate, so I want to be respectful of your time and ensure that the fix is complete and meets the standards of your project. If there are any additional changes that you would like me to make, please do not hesitate to let me know. I am more than happy to work with you to ensure that this fix is implemented correctly.

Thank you for your time and consideration, and I look forward to hearing back from you soon. ❤️

xen0n reviewed Feb 9, 2023

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zhaixiaojuan force-pushed the main branch from 5cf9f8e to 6032821 Compare February 13, 2023 03:49

zhaixiaojuan force-pushed the main branch from 6032821 to 5bb8b14 Compare March 23, 2023 02:06

zhaixiaojuan force-pushed the main branch from 5bb8b14 to 67a4e6e Compare March 31, 2023 02:23

xen0n reviewed Mar 31, 2023

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zhaixiaojuan force-pushed the main branch from 67a4e6e to b11e659 Compare April 4, 2023 06:28

zhaixiaojuan force-pushed the main branch from b11e659 to a6ea0f1 Compare April 10, 2023 03:54

xen0n reviewed Apr 12, 2023

View reviewed changes

Add LoongArch64 support

62fc16b

zhaixiaojuan force-pushed the main branch from a6ea0f1 to 62fc16b Compare April 12, 2023 13:04

sunfishcode merged commit 8217872 into sunfishcode:main Apr 18, 2023

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Add LoongArch64 support #46

Add LoongArch64 support #46

zhaixiaojuan commented Jan 18, 2023

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heiher commented Apr 14, 2023

	# so pre-generated output is used for the time being
	# pre-generated output is used for the time being

Add LoongArch64 support #46

Add LoongArch64 support #46

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zhaixiaojuan commented Jan 18, 2023

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