x86: Add support for FLDENV & FNSTENV

Information
Submitter:	Andreas Sandberg
Repository:	gem5
Branch:	default
Bugs:
Depends On:
Reviewers
Groups:	Default
People:	gblack

Description

Changeset 9760:f7df7b862186
---------------------------
x86: Add support for FLDENV & FNSTENV

Testing Done

Quick regressions pass. Minor stat differences in full regressions (to be expected since some instructions aren't no-ops anymore). Solves a bug triggered by switching between a simulated CPU that tries to save the x87 state and a virtualized CPU that restores the state (which is completely bogus unless FNSTENV is implemented).

Issue Summary

Description	From	Last Updated	Status
Why do we need these eret instructions?	Nilay Vaish	June 28, 2013, 5:16 a.m.	Dropped

Description:

~		Changeset 9759:a3271a8dd7a0
	~	Changeset 9760:f7df7b862186

		x86: Add support for FLDENV & FNSTENV

Diff:

Revision 2 (+98 -16)

Show changes

	src/arch/x86/isa/microasm.isa
	src/arch/x86/isa/decoder/x87.isa
	src/arch/x86/isa/insts/x87/control/save_and_restore_x87_environment.py

Testing Done:

~		Quick regressions pass. Solves a bug triggered by switching between a simulated CPU that tries to save the x87 state and a virtualized CPU that restores the state (which is completely bogus unless FNSTENV is implemented).
	~	Quick regressions pass. Minor stat differences in full regressions (to be expected since some instructions aren't no-ops anymore). Solves a bug triggered by switching between a simulated CPU that tries to save the x87 state and a virtualized CPU that restores the state (which is completely bogus unless FNSTENV is implemented).

src/arch/x86/isa/insts/x87/control/save_and_restore_x87_environment.py (Diff revision 2)

Why do we need these eret instructions?

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Andreas Sandberg June 28, 2013, 5:17 a.m. (June 28, 2013, 5:17 a.m.)

If I understand things correctly, you need to execute eret to return from a microcode sequence (if it's a separate microcode sequence in the microcode rom). There is a new version of this patch that doesn't use microcode rom (I suspected there were issues related to exceptions in microcode, but I'm unsure) in my fixes-x87 branch on GitHub (https://github.com/andysan/gem5/tree/fixes-x87).

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Issue Summary

Description:

Changeset 9759:a3271a8dd7a0

Changeset 9760:f7df7b862186

Diff:

Testing Done:

Status: Closed (submitted)