x86: change divide-by-zero fault to division-error

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Submitter:	Nilay Vaish
Repository:	gem5
Branch:	default
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Description

Changeset 10789:2e0a032f82e0
---------------------------
x86: change divide-by-zero fault to division-error
Same exception is raised whether division with zero is performed or the
quotient is greater than the maximum value that the provided space can hold.

Testing Done

Although I agree that the name "divide-by-zero" is not the most clearly descriptive, that is the name of the exception in the x86 architecture (see for example http://wiki.osdev.org/Exceptions, or Table 2-1 of Vol 3 of the AMD64 Architecture Programmer's Manual. If you think it needs more comments to explain this discrepancy, that's fine, but I think we should keep the exception names consistent with the architecture definition.

Joel Hestness April 19, 2015, 6:43 a.m. (April 19, 2015, 6:43 a.m.)

While I think we should leave the AMD naming, it's probably worth noting/commenting that Intel calls the 0 (#DE) exception a "divide error" in their documentation. http://www.intel.com/Assets/en_US/PDF/manual/253668.pdf, http://ensiwiki.ensimag.fr/images/0/09/4MMPS_traps.pdf

Steve Reinhardt April 19, 2015, 12:25 p.m. (April 19, 2015, 12:25 p.m.)

Thanks for pointing this out, Joel... I looked at the AMD docs then went to see if that was consistent with other usage, saw the osdev.org page, and took that as confirmation that this was common. In practice, it looks like 3rd-party sites are split between the Intel and the AMD terminology. I'm fine with renaming this DivideError to follow the Intel naming. DivisionError doesn't seem consistent with anything else though.

Description:

~		Changeset 10789:42ef8fb0d914
	~	Changeset 10789:2e0a032f82e0

		x86: change divide-by-zero fault to division-error
		Same exception is raised whether division with zero is performed or the
		quotient is greater than the maximum value that the provided space can hold.

Diff:

Revision 2 (+7 -6)

Show changes

	src/arch/x86/faults.hh
	src/arch/x86/isa/microops/regop.isa

Works for me. Thanks, Nilay!

Steve Reinhardt April 20, 2015, 11:18 a.m. (April 20, 2015, 11:18 a.m.)

Actually, now that I said that, you should update the commit message too (since it still says "division-error"). It would be nice to mention that this is the Intel terminology.

You have a pending review.

Review Board 2.0.15

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Description:

Changeset 10789:42ef8fb0d914

Changeset 10789:2e0a032f82e0

Diff:

Status: Closed (submitted)