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Date: Sun, 26 Apr 2009 20:21:22 +0800
From: wuxi <wu.andrew.xi@gmail.com>
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Subject: [Qemu-devel] x86-64 question - QEMU support up to 4GB physical
	memory?
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To: Qemu Development List <qemu-devel@nongnu.org>

Hi, all:
I am hacking QEMU (for fun) based on the 0.10.1 version on x86-64 
architecture. My question arises when I was checking the code of 
PageDesc in QEMU. I found it uses a two level mapping (l1_map), and it 
seems that QEMU can support physical memory up to   2^10 * 2^10 * (4KB) 
= 4GB.

the related code is:

(L1_BITS = 10, L2_BITS=10, TARGET_PAGE_BITS=12)

#define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)
#define L1_SIZE (1 << L1_BITS)
#define L2_SIZE (1 << L2_BITS)

static PageDesc *l1_map[L1_SIZE];

p = qemu_mallocz(sizeof(PageDesc) * L2_SIZE); (for each l1_map entry)

Is this true for QEMU x86-64 emulation? or I made some silly mistakes...

Thanks !

yours sincerely

Andrew