How to rice RPi's ARM1176JZF-S

[necktwi]

How to rice Broadcom BCM2835 @700MHz ARM11 ARM1176JZF-S

currently I've set CFLAGS="-O2 -pipe -march=armv6j -mfpu=vfp -mfloat-abi=hard"

[erm67]

You can try

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cat /proc/cpuinfo 

to see the CPU features

and, since you have a recent gcc,

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gcc -march=native -Q --help=target -v - </dev/null

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gcc -mcpu=native -Q --help=target -v - </dev/null

to see what options are detected by gcc and maybe improve them, detection still isn't perfect on arm.

Usually using -mcpu is more powerful than using -march

[Etal]

You can do:

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-mcpu=arm1176jzf-s

[necktwi]

If i stick in -mcpu=arm1176jzf-s in CFLAGS then emerge says
[bug=]-mcpu=arm1176jzf-s conflicts with -march=armv6j[/bug]

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gcc -march=native -Q --help=target -v - </dev/null

says -march=armv6zk

to rice, should I set -mcpu=arm1176jz-s and -march=armv6zk? or is it same as setting -march=native -mcpu=native or not mentioning -march and -mcpu defaults to native or rpi?

I understand that -mcpu and -march are necessary on crossdev to rice.

[erm67]

If i stick in -mcpu=arm1176jzf-s in CFLAGS then emerge says
[bug=]-mcpu=arm1176jzf-s conflicts with -march=armv6j[/bug]

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gcc -march=native -Q --help=target -v - </dev/null

says -march=armv6zk

to rice, should I set -mcpu=arm1176jz-s and -march=armv6zk? or is it same as setting -march=native -mcpu=native or not mentioning -march and -mcpu defaults to native or rpi?

I understand that -mcpu and -march are necessary on crossdev to rice.

try setting all 3, it shouldn't hurt

-mcpu=arm1176jz-s -march=armv6zk -mtune=arm1176jz-s

Hopefully gcc's native autodetection works for your cpu ...

[necktwi]

But my cpu is arm1176jzf-s, not arm1176jz-s. but

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gcc -mcpu=native -Q --help=target -v - </dev/null

says -mcpu=arm1176jz-s.

what should i use? arm1176jzf-s or arm1176jz-s?

[erm67]

Apparently the 'f' means the CPU has a math coprocessor (FPU), what is the output of
cat /proc/cpuinfo?

If fp or vfp are listed as feautures than probaly gcc is right.

[necktwi]

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(RPi1B2):~ # cat /proc/cpuinfo
processor       : 0
model name      : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS        : 697.95
Features        : half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xb76
CPU revision    : 7

Hardware        : BCM2835
Revision        : 000e
Serial          : 00000000a674e968

so i should use -mcpu=arm1176jz-s as gcc mis-derived? though my processor is arm1176jzf-s?

[erm67]

I told you -march native isn't working correctly on ARM
Use the right one, unless of course -mcpu=arm1176jz-s+fp exists and is the same as arm1176jzf-s, gcc turns on most features by default