RE: [Linux-ia64] Re: [PATCH] head.S fix for unusual load addrs

David Mosberger
2003-05-08T20:29:36Z

>>>>> On Thu, 8 May 2003 10:54:05 -0700, "Luck, Tony" <tony.luck@intel.com> said:

Tony> In fact it might clear up the long standing issue with
Tony> /proc/kcore, if we put the kernel at the low end of region 5
Tony> all the assumptions that module addresses are higher than
Tony> kernel addresses will be valid for ia64 too :-)

Yes, indeed.

Tony> How does this look for an address map?

Tony> 0xA000000000000000 kernel text
Tony> 0xA000000100000000 kernel data
Tony> 0xA000000200000000 percpu area
Tony> 0xA000000300000000 vmalloc & kernel modules
Tony> 0xBFFFFFFxxxxxxxxx CONFIG_VIRTUAL_MEM_MAP

Tony> Reserving an almost arbitrary 4GB for each of kernel
Tony> text/data/percpu (I picked 4GB, since it is the biggest page
Tony> size supported by ia64 ... but other larger boundaries might
Tony> make sense to make the upper level page tables for the vmalloc
Tony> area start on a natural boundary).

I think we may want to reserve the first 4GB for miscellaneous stuff,
such as the start-of-kernel-space-hole, the gate page (and probably
soon a read-only page), and the percpu area. In particular the
guaranteed-not-to-be-mapped page needs to be right at the end of user
space.

--david