Re: [Chicken-users] remove enable/disable interrupt flag

[alaric]

>> AIUI mmap of /dev/zero (to allocate more
>> empty heap) can't block on very much...

>I don't think you can mmap a 
> device, can you?

Sure you can! Mmapping /dev/zero gets you zeroed writable pages and, last I 
looked, is how the heap is obtained. Devices representing frame buffers support 
mapping, too, and map a memory-mapped I/O region into the userland address 
space. Maybe /dev/kmem and friends work for mapping kernel memory, too... Not 
so sure about that. Obviously the likes of ttys don't ;-)

------Original Message------
From: John Cowan
Sender: John Cowan
To: Alaric Snell-Pym
Cc: address@hidden
Cc: address@hidden
Subject: Re: [Chicken-users] remove enable/disable interrupt flag
Sent: 30 Sep 2011 16:47

Alaric Snell-Pym scripsit:

> Yeah. We need to make sure that Chicken's stack limit (which triggers a
> GC) is sufficiently clear of the real stack limit to give us legroom for
> any fun and games that may occur in the runtime.

The chance of a stack blowup is essentially nil.  Chicken, the last time
I looked, has a stack limit of 64K; typical desktop OSes provide stack
sizes in the megabytes by default.

Of course, if you wind up the C stack by having Chicken call C which calls
Chicken which calls C to some serious depth, all bets are off.

> Your other points about multiple signals sugget it should be a proper
> queue, not just a bitmask. Although I have a vague feeling that Unix was
> allowed to coalesce pending signals as it just used a bitmask itself...

In the old days, yes.  Now signals have guaranteed delivery, at least if
you use sigaction() to catch them.  I suspect that most of our systems
in fact will work with signal(), as it's just a thin layer over sigaction(),
but better not to rely on that.

> AIUI mmap of /dev/zero (to allocate more
> empty heap) can't block on very much...

I don't think you can mmap a device, can you?

-- 
I don't know half of you half as well           John Cowan
as I should like, and I like less than half     address@hidden
of you half as well as you deserve.             http://www.ccil.org/~cowan
        --Bilbo



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