From: Blaisorblade <blaisorblade@yahoo.it>
To: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: [uml-devel] About "jiffies" patch
Date: Thu, 13 Jan 2005 06:12:34 +0100 [thread overview]
Message-ID: <200501130612.34417.blaisorblade@yahoo.it> (raw)
Well, effectively your reasoning holds, apart for one point: the code should
not hang because of that large INITIAL_JIFFIES. What we care about are only
the value of jiffies relative to INITIAL_JIFFIES, indeed.
In fact, that code works on 64-bit arch's. But INITIAL_JIFFIES is not 0 to
make sure it wraps 5 minutes after the boot, to make sure the wrapping
mechanism is debugged. And this, currently, does not happen likely.
While on 32-bit archs that construct is like "(unsigned int) (-300*HZ)", on
64-bit archs to get a negative number we'd need something like:
(unsigned long)(long)(-300*HZ)
or
(unsigned long)(-300L*HZ)
so that the number is first sign-extended and then casted to unsigned.
--
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade
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next reply other threads:[~2005-01-13 5:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-13 5:12 Blaisorblade [this message]
2005-01-15 2:06 ` [uml-devel] About "jiffies" patch Blaisorblade
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