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gabord
n00b
Joined: 17 Sep 2018
Posts: 3
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 Posted: Mon Sep 17, 2018 6:10 am Post subject: Cross emerge gcc with which -march? |
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Hi,
I would like to cross emerge gcc with the following command (and -march=armv8-a+crc set) on an amd64 build machine, but I get an error message.
| Code: | aarch64-unknown-linux-gnu-emerge gcc
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| Code: | cc1plus: error: bad value (‘armv8-a+crc’) for ‘-march=’ switch
cc1plus: note: valid arguments to ‘-march=’ switch are: nocona core2 nehalem corei7 westmere sandybridge corei7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 cannonlake icelake-client icelake-server bonnell atom silvermont slm knl knm x86-64 eden-x2 nano nano-1000 nano-2000 nano-3000 nano-x2 eden-x4 nano-x4 k8 k8-sse3 opteron opteron-sse3 athlon64 athlon64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 btver1 btver2 native
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Every other package compiles correctly (around ~200), except this.
If I set -march to be the build architecture, gcc cross emerges, but none of the other packages do. I do not think this is a correct behavior for gcc, because -march means the target architecture, and not the build architecture, isn't it?
Which CFLAGS should I use?
The same thing happens with gcc-7.3.0-r3 and 8.2.0-r2.
My /usr/aarch64-unknown-linux-gnu/etc/portage/make.conf file:
| Code: | ROOT=/usr/aarch64-unknown-linux-gnu/
ACCEPT_KEYWORDS="~arm64"
CFLAGS="-march=armv8-a+crc -O2 -pipe"
CXXFLAGS="${CFLAGS}"
PORTAGE_TMPDIR=${ROOT}var/tmp/
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Full build log: https://pastebin.com/bbWiZF6y |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54234
Location: 56N 3W
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| Posted: Mon Sep 17, 2018 7:35 am Post subject: |
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gabord,
Welcome to Gentoo.
Do not set -march at all, just for gcc, while it is cross compiled.
The output gcc will run on any arm64 system and will itself obey the -march= when you run it on the target.
You can have portage set per package CFLAGS using both /etc/portage/env/ and /etc/portage/package.env/
-- edit --
That's the /usr/aarch64-unknown-linux-gnu/ ... files.
_________________
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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gabord
n00b
Joined: 17 Sep 2018
Posts: 3
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| Posted: Mon Sep 17, 2018 7:50 am Post subject: |
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| NeddySeagoon wrote: | | Welcome to Gentoo. |
Thanks!
| NeddySeagoon wrote: | | Do not set -march at all, just for gcc, while it is cross compiled. |
I will do that. What is the reason for this? Can I read about that in detail why gcc needs does this for cross compile? I tried to find information about the toolchain eclass, but could not find any. |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54234
Location: 56N 3W
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| Posted: Mon Sep 17, 2018 7:54 am Post subject: |
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gabord,
The simple answer is that its a feature of the gcc build system.
Leaving out -march is a workaround, not a fix.
If you want to save some build time, I have a an arm64 BINHOST that is publicly accessible.
_________________
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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gabord
n00b
Joined: 17 Sep 2018
Posts: 3
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| Posted: Mon Sep 17, 2018 6:52 pm Post subject: |
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| NeddySeagoon wrote: | gabord,
The simple answer is that its a feature of the gcc build system.
Leaving out -march is a workaround, not a fix.
If you want to save some build time, I have a an arm64 BINHOST that is publicly accessible. |
Thanks! And I will look into it in detail in the future why this is a feature, but it is not important now. |
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