Date: Tue, 1 Feb 2000 17:05:50 -0800 (PST) From: Chee Wei Ng <scip7050@yahoo.com> To: freebsd-smp@freebsd.org Subject: MPrellock_edx Message-ID: <20000202010550.16864.qmail@web112.yahoomail.com>
next in thread | raw e-mail | index | archive | help
Hi,
I would like to know why we need
lock
addl $0,0(%esp) /* see note above */
for serialization.
Could you show me an example for MP case where it may cause trouble if the
above lines are not added in it?
Because I didn't see how instruction execution out of order come into the
picture since before any processors enter the Critical Section, it has to
acquire the mplock first, and acquire the mplock, you must 'LOCK' the bus cycle
to serialize the mplock flag to be read-modify-write, so I thought here will do
all the serialization as required. Unless, it could be something that may needs
to serialize for access before this.
Thanks.
Rgds,
NgCW
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-smp" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20000202010550.16864.qmail>