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Date: Wed, 22 Aug 2012 10:20:26 +0800
From: =?utf-8?B?6Zmz6Z+L5Lu7IChXZWktUmVuIENoZW4p?= <chenwj@iis.sinica.edu.tw>
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Subject: Re: [Qemu-devel] Dump guest page table inside QEMU makes system hang
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-devel@nongnu.org, =?utf-8?B?6Zmz6Z+L5Lu7IChXZWktUmVuIENoZW4p?= <chenwj@iis.sinica.edu.tw>

> >   The system will hang while booting. However, if I comment
> > cpu_physical_memory_read in function dump_guest_pgtable, there
> > is no problem. What I am missing here? Thanks.
>=20
> cpu_physical_memory_read() can cause faults or other side effects like
> MMIO. Using cpu_get_phys_page_debug() may help.

  PMM also suggest me looking on cpu_get_phys_page_debug. When I read
the code, I found something suspicious.

---
target_phys_addr_t cpu_get_phys_page_debug(CPUX86State *env, target_ulong=
 addr)
{
    target_ulong pde_addr, pte_addr;

    ...

    pde =3D ldq_phys(pde_addr);

    ...
}
---

  The address of pde and pte should be (guest) physical address, right?
If so, then target_ulong should be replaced with target_phys_addr_t.
The other clue is the type of ldq_phys's parameter is target_phys_addr_t.

Regards,
chenwj

--=20
Wei-Ren Chen (=E9=99=B3=E9=9F=8B=E4=BB=BB)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj