cvs commit: src/sys/amd64/amd64 genassym.c locore.S machdep.c mem.c nexus.c pmap.c trap.c vm_machdep.c src/sys/amd64/include bus_amd64.h param.h pmap.h vmparam.h src/sys/conf kern.mk

[Ruslan Ermilov]

On Thu, May 22, 2003 at 11:21:45PM -0700, Peter Wemm wrote:
> Dag-Erling Smorgrav wrote:
> > Peter Wemm <peter at FreeBSD.org> writes:
> > >   - The kernel is moved into the negative address space(!).
> > 
> > Read a lot of Knuth lately?  :)
> 
> Heh, no.  Its just a quirk of doing signed 32 and 48 bit addressing.  Gcc
> likes to generate 32 bit signed address relocations in the code generation
> models that we use.  This means it can reference symbols from -2GB through
> 2GB.  There are 48 virtual address bits (256TB) that are defined in this
> version of the cpu spec, and it too is signed.  So, it just seemed natural
> to have the user own the positive half, and the kernel the negative half.
> This probably isn't strictly necessary, we could allocate additional user
> address space in the unused negative address space if 128TB isn't enough.
> :-)
> 
amd64 isn't going to be positive, EvilKernel?  ;)


Cheers,
-- 
Ruslan Ermilov		Sysadmin and DBA,
ru at sunbay.com		Sunbay Software AG,
ru at FreeBSD.org		FreeBSD committer,
+380.652.512.251	Simferopol, Ukraine

http://www.FreeBSD.org	The Power To Serve
http://www.oracle.com	Enabling The Information Age
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