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chromatic abberation
n00b
Joined: 28 Jan 2023
Posts: 2
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 Posted: Sat Jan 28, 2023 8:55 pm Post subject: Can't change LLVM_TARGETS for llvm and clang |
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Been trying to emerge llvm but can't emerge llvm for just X86 arch. It tries to compile it for other architectures too!
I tried to follow https://bugs.gentoo.org/767700 which was referenced from https://forums.gentoo.org/viewtopic-p-8694149.html.
Running emerge -pv --nodeps llvm rust clang gives this.
| Code: | emerge -pv --nodeps llvm rust clang
These are the packages that would be merged, in order:
[ebuild N ] sys-devel/llvm-15.0.7:15::gentoo USE="binutils-plugin libffi ncurses -debug -doc -exegesis -libedit -test -verify-sig -xar -xml -z3 -zstd" ABI_X86="(64) -32 (-x32)" LLVM_TARGETS="(AArch64) (AMDGPU) (ARM) (AVR) (BPF) (Hexagon) (Lanai) (MSP430) (Mips) (NVPTX) (PowerPC) (RISCV) (Sparc) (SystemZ) (VE) (WebAssembly) (X86) (XCore) (-ARC) (-CSKY) (-DirectX) (-LoongArch) (-M68k) (-SPIRV)" 108,579 KiB
[ebuild N ] dev-lang/rust-1.66.1:stable/1.66::gentoo USE="-clippy -debug -dist -doc (-llvm-libunwind) (-miri) (-nightly) (-parallel-compiler) (-profiler) -rust-analyzer -rust-src -rustfmt (-system-bootstrap) (-system-llvm) -test -verify-sig -wasm" ABI_X86="(64) -32 (-x32)" CPU_FLAGS_X86="sse2" LLVM_TARGETS="(X86) -AArch64 -AMDGPU -ARM -AVR -BPF -Hexagon -Lanai -MSP430 -Mips -NVPTX -PowerPC -RISCV -Sparc -SystemZ -WebAssembly -XCore" 296,603 KiB
[ebuild N ] sys-devel/clang-15.0.7-r1:15/15g1::gentoo USE="extra (pie) static-analyzer -debug -doc (-ieee-long-double) -test -verify-sig -xml" ABI_X86="(64) -32 (-x32)" LLVM_TARGETS="(AArch64) (AMDGPU) (ARM) (AVR) (BPF) (Hexagon) (Lanai) (MSP430) (Mips) (NVPTX) (PowerPC) (RISCV) (Sparc) (SystemZ) (VE) (WebAssembly) (X86) (XCore) (-ARC) (-CSKY) (-DirectX) (-LoongArch) (-M68k) (-SPIRV)" PYTHON_SINGLE_TARGET="python3_10 -python3_9 -python3_11" 0 KiB
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Only rust seems to take LLVM_TARGETS as X86 and not others.
Also tried setting LLVM_TARGETS="X86" on make.conf but it doesn't respect it. How to fix this? |
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Hu
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Joined: 06 Mar 2007
Posts: 22474
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| Posted: Sat Jan 28, 2023 10:51 pm Post subject: |
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Those flags are forced on by $PORTDIR/profiles/base/package.use.force: | Code: | # Michał Górny <mgorny@gentoo.org> (2021-11-04)
# Enable all LLVM targets unconditionally. Unfortunately, disabling
# targets tend to break reverse dependencies (e.g. Rust) and we are yet
# to find a clean way of resolving that. Compared to the damage
# potential, the increase of build time is a minor problem. Users who
# really insist of building a smaller system can un-force the flags
# at their own responsibility.
>=sys-devel/clang-13.0.1_rc llvm_targets_AArch64 llvm_targets_AMDGPU
>=sys-devel/clang-13.0.1_rc llvm_targets_ARM llvm_targets_AVR llvm_targets_BPF
>=sys-devel/clang-13.0.1_rc llvm_targets_Hexagon llvm_targets_Lanai
>=sys-devel/clang-13.0.1_rc llvm_targets_MSP430 llvm_targets_Mips
>=sys-devel/clang-13.0.1_rc llvm_targets_NVPTX llvm_targets_PowerPC
>=sys-devel/clang-13.0.1_rc llvm_targets_RISCV llvm_targets_Sparc
>=sys-devel/clang-13.0.1_rc llvm_targets_SystemZ llvm_targets_WebAssembly
>=sys-devel/clang-13.0.1_rc llvm_targets_X86 llvm_targets_XCore
>=sys-devel/clang-14 llvm_targets_VE
>=sys-devel/clang-16 llvm_targets_LoongArch
>=sys-devel/llvm-13.0.1_rc llvm_targets_AArch64 llvm_targets_AMDGPU
>=sys-devel/llvm-13.0.1_rc llvm_targets_ARM llvm_targets_AVR llvm_targets_BPF
>=sys-devel/llvm-13.0.1_rc llvm_targets_Hexagon llvm_targets_Lanai
>=sys-devel/llvm-13.0.1_rc llvm_targets_MSP430 llvm_targets_Mips
>=sys-devel/llvm-13.0.1_rc llvm_targets_NVPTX llvm_targets_PowerPC
>=sys-devel/llvm-13.0.1_rc llvm_targets_RISCV llvm_targets_Sparc
>=sys-devel/llvm-13.0.1_rc llvm_targets_SystemZ llvm_targets_WebAssembly
>=sys-devel/llvm-13.0.1_rc llvm_targets_X86 llvm_targets_XCore |
As the note says, if you need to disable them and are willing to take the risks, you can negate the forced configuration and then disable them.
Rust does not force these flags on because it does not have any reverse dependencies that are known to be sensitive to changing them. |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54553
Location: 56N 3W
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| Posted: Sat Jan 28, 2023 11:01 pm Post subject: |
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chromatic abberation,
Welcome to Gentoo.
| Code: | | LLVM_TARGETS="(AArch64) (AMDGPU) (ARM) (AVR) (BPF) (Hexagon) (Lanai) (MSP430) (Mips) (NVPTX) (PowerPC) (RISCV) (Sparc) (SystemZ) (VE) (WebAssembly) (X86) (XCore) (-ARC) (-CSKY) (-DirectX) (-LoongArch) (-M68k) (-SPIRV)" |
The parenthesis () indicates that the option is forced by your profile. Some are forced on, others are forced off.
Before you can change forced settings you need to override your profile to remove the ().
Then LLVM_TARGETS= in make.conf will allow you to change the settings.
If you make entries in /etc/portage/profile/use.mask they will affect all packages that accept those USE flags.
Entries in /etc/portage/profile/package.use.mask are per package.
See https://wiki.gentoo.org/wiki//etc/portage/profile/use.mask and https://wiki.gentoo.org/wiki///etc/portage/profile/package.use.mask.
You also need to know that LLVM_TARGETS is a use expand, so it expands to llvm_targets_AArch64 llvm_targets_AMDGPU ...
I'm not sure if the short form is accepted or not.
That's all the bits you need. I'll leave it for you to put all the bits together, or post back if you need more explicit help.
It may make more problems than it fixes though.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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chromatic abberation
n00b
Joined: 28 Jan 2023
Posts: 2
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| Posted: Sun Jan 29, 2023 8:49 am Post subject: |
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Thanks Hu and NeddySeagoon. 
Masking them in /etc/portage/profile/package.use.mask did the trick.
Is this a bug with using the hardened profile? |
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sam_
Developer
Joined: 14 Aug 2020
Posts: 1909
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| Posted: Sun Jan 29, 2023 8:56 am Post subject: |
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| chromatic abberation wrote: | Thanks Hu and NeddySeagoon.
Masking them in /etc/portage/profile/package.use.mask did the trick.
Is this a bug with using the hardened profile? |
No, see Hu's post. Understand the risks (inc. why they're masked in the first place) before unforcing. |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54553
Location: 56N 3W
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| Posted: Sun Jan 29, 2023 9:37 am Post subject: |
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chromatic abberation,
Answering questions is one thing. How you apply your new knowledge is another.
If you shoot yourself in the foot, that's OK too.
Be aware that this may break other things and as the warning says, you will end up spending more than the build time you have saved recovering.
It's your Gentoo, your way.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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dennisn
Tux's lil' helper
Joined: 01 Aug 2004
Posts: 119
Location: Montreal, Canada
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| Posted: Sun Dec 24, 2023 6:19 pm Post subject: |
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| I don't understand why these targets are forced - why would I ever need an ARM target, for example? (I don't have ARM hardware.) |
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Hu
Administrator
Joined: 06 Mar 2007
Posts: 22474
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| Posted: Sun Dec 24, 2023 6:58 pm Post subject: |
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| dennisn wrote: | | I don't understand why these targets are forced - why would I ever need an ARM target, for example? (I don't have ARM hardware.) |
That is explained in the comment from mgorny that I showed back when the thread was new. In short, changing it after other things have come to depend on it is likely to cause problems due to how the flag is interpreted. |
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dennisn
Tux's lil' helper
Joined: 01 Aug 2004
Posts: 119
Location: Montreal, Canada
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| Posted: Sun Dec 24, 2023 7:04 pm Post subject: |
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| I read that short explanation, I'm looking for more clarity/depth. Again, I have no ARM hardware, so why should I compile it as a "target", for example. (Actually I am forced to use the AMDGPU target, even though I'm pretty sure I don't have anything AMD here. Confusing.) |
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Havin_it
Veteran
Joined: 17 Jul 2005
Posts: 1259
Location: Edinburgh, UK
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| Posted: Sun Jul 07, 2024 3:48 pm Post subject: |
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I'm also intrigued about this. Especially I'm wondering if the situation has evolved at all in the past 6 months, after looking at the current ebuilds for the two packages cited as being under breakage-risk from force-disabling targets.
dev-lang/zig/zig-0.12.0.ebuild does not mention LLVM_TARGETS at all. If, as is stated, it needs *all* targets enabled, shouldn't it be enforcing this?
dev-lang/rust/rust-1.78.0.ebuild contains a list of LLVM_TARGETS but I don't understand ebuild syntax well enough to say whether it is requiring llvm to have all these targets enabled, or is actually modifying what targets it builds according to the current llvm's flags.
I've not seen any other packages mentioned as affected, though I imagine those built with the above are affected. And both have -bin ebuilds for which I'd assume it is moot.
I get that this is a knotty problem to solve and justifiably low on any dev's priority list, and I'm nowadays lucky enough to have reasonably powerful hardware within my budget anyway, but my Gentoo sensibilities still abhor the redundancy. And I can't help being a little sceptical about the resource cost of all these added, unnecessary targets really being "negligible". By what measurement? |
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