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| From: | Laszlo Ersek |
| Subject: | Re: [Qemu-devel] [Xen-devel] qemu(-dm): aborting on wrong mmio size? |
| Date: | Tue, 31 Jan 2012 12:04:14 +0100 |
| User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.24) Gecko/20111104 Red Hat/3.1.16-2.el6_1 Mnenhy/0.8.4 Thunderbird/3.1.16 |
On 01/31/12 11:36, Jan Beulich wrote:
On 31.01.12 at 10:34, Laszlo Ersek<address@hidden> wrote:
Is it justified to kill the emulator when this happens (eg. memory mapped IO with 64-bit operand)?
The AMD manual specifies that REX.W is ignored; the Intel manual doesn't mention REX at all here. However, if a decoder incorrectly decodes the guest instruction, that's a bug there. So imo qemu validly treats this condition as fatal.
From the Itanium(R) SDM rev 2.3,
10.7.2.1 I/O Port Addressing Restrictions
For the 64MB physical I/O port block the following operations are
undefined and may result in unpredictable processor operation;
references larger than 4-bytes, [...]
It seems that not only a decoding failure can trigger this.
Laszlo
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