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#1 2010-05-28 18:22:22

MickST
Member
Registered: 2010-02-26
Posts: 54

[SOLVED] Linux kernel and custom CFLAGS.

I know the Linux kernel is quite tight to the CFLAGS that can be used to build it, but I'd like to know if there is a way to get to know which compilation flags are being used in a build and how/where to modify them.

I'm building a custom kernel selecting Core2 as the targeted processor type, but SSE+ instructions are not being enabled, so -march=core2 is not being used.

Last edited by MickST (2010-05-29 00:43:37)

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#2 2010-05-28 18:40:10

falconindy
Developer
From: New York, USA
Registered: 2009-10-22
Posts: 4,095
Website

Re: [SOLVED] Linux kernel and custom CFLAGS.

The kernel uses its own set of CFLAGS, KCFLAGS.

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#3 2010-05-29 00:43:16

MickST
Member
Registered: 2010-02-26
Posts: 54

Re: [SOLVED] Linux kernel and custom CFLAGS.

Yes, it uses its internal compilation flags, and it's better not to touch them a lot.

From what I've seen the actual march option is set in a file inside of the arch directory. For the Core2 selection the march is set to i686 and mtune to core2. Setting march to core2 there would make nothing really as SSE and cia are explicitly unset in the makefile of that directory.

Thank you for the answer though.

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