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Hi everyone, |
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|
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I'm just in the middle of compiling some applications in the |
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media-video category for a pxa270 device, and I'm seeing a lot of |
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spots where potential iWMMXT hardware speedups are not being used |
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because I'm using CFLAGS="-march=armv5te -mtune=xscale". One person |
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said, there is only a difference between -mcpu=xscale and -mcpu=iwmmxt |
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when using OABI [1]. However, the -mtune=xscale flag does not properly |
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process iwmmxt instructions [2]. Is -mcpu=xscale only for pre-iwmmxt |
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pxa chips? |
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|
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Does anyone know exactly which CFLAGS should be used for a pxa270 chip? |
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|
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A binary compiled with -mcpu=iwmmxt still shows that it has version 4 |
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EABI, which is fine for me. I just find it odd that XScale ISA is |
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supposedly identical to armv5te aside from FP instructions [3], while |
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gcc fails saying that "-march=armv5te -mtune=iwmmxt" is not kosher |
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[4]. |
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|
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Chris |
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|
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[1] http://gcc.gnu.org/ml/gcc-help/2006-09/msg00061.html |
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[2] int main(void) { __asm__ volatile ("wunpckelub wr6, wr4"); return 0; } |
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[3] http://en.wikipedia.org/wiki/XScale |
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[4] arm-softfloat-linux-gnueabi-gcc -pipe -march=armv5te -mtune=xscale |
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-o test test.c |
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{standard input}: Assembler messages: |
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{standard input}:13: Error: selected processor does not support |
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`wunpckelub wr6,wr4' |
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