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Re: [Qemu-devel] [PATCH 02/10 v11] linux-user: Support tilegx architectu


From: Chris Metcalf
Subject: Re: [Qemu-devel] [PATCH 02/10 v11] linux-user: Support tilegx architecture in linux-user
Date: Wed, 3 Jun 2015 11:20:42 -0400
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0

On 06/03/2015 11:19 AM, Peter Maydell wrote:
On 3 June 2015 at 16:10, Chris Metcalf <address@hidden> wrote:
On 06/03/2015 08:47 AM, Chen Gang wrote:
On 06/03/2015 08:34 PM, Peter Maydell wrote:
You must do something. You can't allow guest code (even
broken guest code) to make QEMU assert. You need to find
out what the hardware does here, and do that.

OK, what you said sounds reasonable to me. I will check what to do next
for the 56..62 registers (at present, I guess, we need generate a
hardware exception, and its default handler will do nothing).

The registers in question are mapped directly to the on-chip
networks.

56 - sn (static network)
57 - idn0 (internal dynamic network, demux 0)
58 - idn1 (internal dynamic network, demux 1)
59 - udn0 (user dynamic network, demux 0)
60 - udn1 (user dynamic network, demux 1)
61 - udn2 (user dynamic network, demux 2)
62 - udn3 (user dynamic network, demux 3)

The "sn" is obsoleted in tilegx so acts just like "zero".

Accessing idn0 or idn1 will generate an IDN_ACCESS exception,
and accessing udn0..udn3 will generate a UDN_ACCESS exception;
either of those becomes a SIGILL to a userspace application
with code ILL_PRVREG.
Presumably this applies for all register accesses, not
just atomic instructions?

Correct.

--
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com




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