From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Mark McLoughlin <markmc@redhat.com>,
xen-devel <xen-devel@lists.xensource.com>,
Eduardo Habkost <ehabkost@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Stephen Tweedie <sct@redhat.com>
Subject: Re: [Xen-devel] Re: [PATCH 00 of 36] x86/paravirt: groundwork for 64-bit Xen support
Date: Wed, 25 Jun 2008 20:22:58 +0100 [thread overview]
Message-ID: <C48859A2.231C5%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <20080625191315.GD6708@one.firstfloor.org>
On 25/6/08 20:13, "Andi Kleen" <andi@firstfloor.org> wrote:
>> What does Linux expect to scale up to? Reserving 16 PML4 entries leaves the
>> kernel with 120TB of available 'negative' address space. Should be plenty, I
>> would think.
>
> There are already (ok non x86-64) systems shipping today with 10+TB of
> addressable memory. 100+TB is not that far away with typical
> growth rates. Besides there has to be much more in the negative address
> space than just direct mapping.
There are obviously no x64 boxes around at the moment with >1TB of regular
shared memory, since no CPUs have more than 40 address lines. 100+TB RAM is
surely years away.
If this is a blocker issue, we could just keep PAGE_OFFSET as it is when Xen
support is not configured into the kernel. Then those who are concerned
about 5% extra headroom at 100TB RAM sizes can configure their kernel
appropriately.
> So far we always that 64bit Linux can support upto 1/4*max VA memory.
> With your change that formula would be not true anymore.
Does the formula have any practical significance?
-- Keir
next prev parent reply other threads:[~2008-06-25 19:23 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-25 4:18 [PATCH 00 of 36] x86/paravirt: groundwork for 64-bit Xen support Jeremy Fitzhardinge
2008-06-25 4:18 ` [PATCH 01 of 36] x86: asm-x86/pgtable.h: fix compiler warning Jeremy Fitzhardinge
2008-06-25 4:18 ` [PATCH 02 of 36] x86: add memory clobber to save/loadsegment Jeremy Fitzhardinge
2008-06-25 4:18 ` [PATCH 03 of 36] x86: add memory barriers to wrmsr Jeremy Fitzhardinge
2008-06-25 4:44 ` Arjan van de Ven
2008-06-25 21:08 ` Jeremy Fitzhardinge
2008-06-25 22:31 ` Arjan van de Ven
2008-06-25 23:05 ` Jeremy Fitzhardinge
2008-06-25 23:18 ` H. Peter Anvin
2008-06-25 23:37 ` Jeremy Fitzhardinge
2008-06-25 23:42 ` H. Peter Anvin
2008-06-25 4:19 ` [PATCH 04 of 36] x86: remove open-coded save/load segment operations Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 05 of 36] x86_64: use write_gdt_entry in vsyscall_set_cpu Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 06 of 36] x86_64: use p??_populate() to attach pages to pagetable Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 07 of 36] x86_64: unify early_ioremap Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 08 of 36] x86_64: Add gate_offset() and gate_segment() macros Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 09 of 36] x86_64: Use __pgd() on mk_kernel_pgd() Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 10 of 36] x86: unify pgd_index Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 11 of 36] x86: unify mmu_context.h Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 12 of 36] x86_64: replace end_pfn with num_physpages Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 13 of 36] x86_64: add prototype for x86_64_start_kernel() Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 14 of 36] x86_64: add sync_cmpxchg Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 15 of 36] x86: simplify vmalloc_sync_all Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 16 of 36] x86/paravirt: add a pgd_alloc/free hooks Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 17 of 36] x86: preallocate and prepopulate separately Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 18 of 36] x86/paravirt: add debugging for missing operations Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 19 of 36] paravirt_ops: define PARA_INDIRECT for indirect asm calls Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 20 of 36] paravirt/x86_64: move __PAGE_OFFSET to leave a space for hypervisor Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 21 of 36] x86-64: add FIX_PARAVIRT_BOOTMAP fixmap slot Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 22 of 36] x86_64: split x86_64_start_kernel Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 23 of 36] x86_64: adjust mapping of physical pagetables to work with Xen Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 24 of 36] x86_64: create small vmemmap mappings if PSE not available Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 25 of 36] x86_64: PSE no longer a hard requirement Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 26 of 36] x86_64: Split set_pte_vaddr() Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 27 of 36] x86_64: __switch_to(): Move arch_leave_lazy_cpu_mode() to the right place Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 28 of 36] Save %fs and %gs before load_TLS() and arch_leave_lazy_cpu_mode() Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 29 of 36] Use __KERNEL_DS as SS when returning to a kernel thread (VERIFY) Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 30 of 36] x86/paravirt_ops: split sysret and sysexit Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 31 of 36] x86_64 pvops: don't restore user rsp within sysret Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 32 of 36] Add sysret/sysexit pvops for returning to 32-bit compatibility userspace Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 33 of 36] x86_64: ia32entry: replace privileged instructions with pvops Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 34 of 36] x86_64: swapgs pvop with a user-stack can never be called Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 35 of 36] x86_64/paravirt: add adjust_exception_frame Jeremy Fitzhardinge
2008-06-25 4:19 ` [PATCH 36 of 36] x86_64/paravirt: Make load_gs_index() a paravirt operation Jeremy Fitzhardinge
2008-06-25 8:47 ` Ingo Molnar
2008-06-25 11:48 ` Jeremy Fitzhardinge
2008-06-25 8:42 ` [PATCH 00 of 36] x86/paravirt: groundwork for 64-bit Xen support Ingo Molnar
2008-06-25 11:46 ` Jeremy Fitzhardinge
2008-06-25 15:22 ` Ingo Molnar
2008-06-25 20:12 ` Jeremy Fitzhardinge
2008-06-26 10:57 ` Ingo Molnar
2008-06-26 10:58 ` Ingo Molnar
2008-06-26 14:34 ` [Xen-devel] " Jeremy Fitzhardinge
2008-06-27 15:56 ` Ingo Molnar
2008-06-27 16:02 ` Jeremy Fitzhardinge
2008-06-27 16:06 ` Ingo Molnar
2008-06-27 16:25 ` Jeremy Fitzhardinge
2008-06-27 16:03 ` Ingo Molnar
2008-06-27 19:04 ` Jeremy Fitzhardinge
2008-06-29 8:43 ` Ingo Molnar
2008-06-30 3:02 ` Jeremy Fitzhardinge
2008-06-30 4:35 ` Yinghai Lu
2008-06-30 5:32 ` Jeremy Fitzhardinge
2008-06-30 8:21 ` Ingo Molnar
2008-06-30 9:22 ` Ingo Molnar
2008-06-30 17:17 ` Jeremy Fitzhardinge
2008-06-30 18:12 ` Ingo Molnar
2008-06-30 18:36 ` Jeremy Fitzhardinge
2008-06-30 18:44 ` Ingo Molnar
2008-06-30 17:57 ` Jeremy Fitzhardinge
2008-06-30 18:03 ` Ingo Molnar
2008-06-30 23:04 ` Jeremy Fitzhardinge
2008-07-01 8:52 ` Ingo Molnar
2008-07-01 9:21 ` Ingo Molnar
2008-07-01 16:10 ` Jeremy Fitzhardinge
2008-07-01 16:14 ` Jeremy Fitzhardinge
2008-07-01 20:31 ` Ingo Molnar
2008-07-03 9:10 ` Ingo Molnar
2008-07-03 15:47 ` Jeremy Fitzhardinge
2008-07-03 18:20 ` Yinghai Lu
2008-07-03 18:25 ` Jeremy Fitzhardinge
2008-07-03 18:30 ` Yinghai Lu
2008-07-03 18:41 ` Jeremy Fitzhardinge
2008-07-03 18:51 ` Yinghai Lu
2008-07-03 19:19 ` Yinghai Lu
2008-07-03 19:29 ` Yinghai Lu
2008-07-09 7:42 ` Ingo Molnar
2008-06-26 14:28 ` Jeremy Fitzhardinge
2008-06-26 18:25 ` Jeremy Fitzhardinge
2008-06-26 19:02 ` Jeremy Fitzhardinge
2008-06-25 12:40 ` Andi Kleen
2008-06-25 18:45 ` [Xen-devel] " Keir Fraser
2008-06-25 19:13 ` Andi Kleen
2008-06-25 19:22 ` Keir Fraser [this message]
2008-06-25 20:14 ` Andi Kleen
2008-06-25 20:03 ` Jeremy Fitzhardinge
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