Date: Mon, 03 Apr 2006 15:23:12 -0600 From: Scott Long <scottl@samsco.org> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: freebsd-amd64@freebsd.org Subject: Re: Status of NX bit support. Message-ID: <44319240.8070203@samsco.org> In-Reply-To: <20060403211943.GA99241@troutmask.apl.washington.edu> References: <44301C6D.3010206@rogers.com> <200604031442.43477.jhb@freebsd.org> <44318E3F.6080808@rogers.com> <20060403211943.GA99241@troutmask.apl.washington.edu>
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Steve Kargl wrote: > On Mon, Apr 03, 2006 at 05:06:07PM -0400, Mike Jakubik wrote: > >>John Baldwin wrote: >> >>>On Sunday 02 April 2006 14:48, Mike Jakubik wrote: >>> >>> >>>>I was wondering what the status of the NX bit support is. Is the pmap.c >>>>code still broken or is support enabled and functioning by default? >>>> >>> >>>I don't think the status has changed. >>> >>> >> >>Well that sucks.. I guess then there really is no reason for someone to >>run in amd64 mode unless you need more than 4GB of ram. >> > > > You're joking, right? How many registers are available for the > i386? How many registers are available to an AMD64 cpu in > 64-bit mode? > You also get less efficient cache utilization due to the wider data types that are in use. It seems to be mostly a wash between the advantages of more registers and the cost of lower cache efficiency. amd64 is nice when you need more kernel address space and/or more process address space. Scott
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