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Re: jiffies

Arun Sharma forced the electrons to say:
> > Will the system go haywire if the uptime goes beyond this limit?
> It may. Specifically if your machine has a driver, that has the
> following code:
> now = jiffies;
> future = now + HZ * 2;
> /* Wait for two seconds */
> while (jiffies < future) /* do nothing */;
> Such code will hang for 497 days, locking up your system.

The reason I asked this question was, I downloaded the pcmcia-cs package, and
noticed this sort of thing in one of the modules it builds (specifically,

static void
busy_loop(u_long len)
    if (in_interrupt()) {
	u_long timeout = jiffies + len;
	u_long flags;
	while (timeout >= jiffies)
    } else {

Maybe they figured laptops won't have uptimes of 400+ days. :-)

> One common technique is to set jiffies to 0xffffffff - 1 hour, when you
> boot your system. A faulty driver will lock up in an hour.

How do you do that? set it in the kernel code itself and recompile?


The prompt for all occasions:
export PS1="F:\$(pwd | tr '/[a-z]' '\134\134[A-Z]')> "
--------------- Binand Raj S. (binand@xxxxxxxxxxxxxxxxxxxxx)