[syslinux] proper way to sleep

[H. Peter Anvin]

Erwan Velu wrote:
> I had the same problem in my com32 modules.. It could be nice to add a 
> sleep(unsigned int msec) function.
> 
> Can't we use such code ?
> 
> unsigned char sleep(unsigned int msec)
> {
>    unsigned long micro = 1000*msec;
>    com32sys_t inreg,outreg;
>    REG_AH(inreg) = 0x86;
>    REG_CX(inreg) = (micro >> 16);
>    REG_DX(inreg) = (micro & 0xFFFF);
>    __intcall(0x15,&inreg,&outreg);
>    return REG_AH(outreg);
> }

No, please spin on syslinux_idle(), at least for anything other than a
trivial delay.  Especially PXELINUX tends to need to perform tasks while
spinning.

	-hpa