[maemo-developers] N800 & Video playback

[From: Tao Huang]

Siarhei Siamashka 写道:
> I have seen your code in xserver which does the same job for downscaling, but
> in nonoptimized C and with much higher impact on quality. Using JIT scaler
> there can improve both image quality and performance a lot. The only my
> concern is about instruction cache coherency. As ARM requires explicit
> instructions cache flush for self modyfying or dynamically generated code, I
> wonder if  using just mmap is safe (does it flush cache for allocated region
> of  memory?). Maybe maemo kernel hackers/developers can help with this
> information?
>   
arm linux support flush icache by syscall "cacheflush",

qemu have this function:
static inline void flush_icache_range(unsigned long start, unsigned long 
stop)
{
    register unsigned long _beg __asm ("a1") = start;
    register unsigned long _end __asm ("a2") = stop;
    register unsigned long _flg __asm ("a3") = 0;
    __asm __volatile__ ("swi 0x9f0002" : : "r" (_beg), "r" (_end), "r" 
(_flg));
}

you can reference kernel source arch/arm/kernel/traps.c and 
include/asm-arm/unistd.h