Bug 188

Summary:	consider adding old-hardware compatibility mode to FPU
Product:	Libre-SOC's first SoC	Reporter:	Jacob Lifshay <programmerjake>
Component:	Specification	Assignee:	Luke Kenneth Casson Leighton <lkcl>
Status:	CONFIRMED ---
Severity:	enhancement	CC:	libre-soc-bugs, programmerjake
Priority:	---
Version:	unspecified
Hardware:	All
OS:	All
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budget (EUR) for this task, excluding subtasks' budget:	0	parent task for budget allocation:
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Description Jacob Lifshay 2020-02-24 23:29:38 GMT

See thread at:
https://lists.freedesktop.org/archives/mesa-dev/2020-February/224144.html

This can be done by either having a mode CSR or by using different instructions.

One particular case is where IEEE specifies that 0.0 * Infinity == NaN, old hardware calculates the result as 0.0 * Infinity == 0.0

Note that we would probably need a new Vulkan extension to support this, since Vulkan specifies following IEEE here (from what I recall).

Comment 1 Luke Kenneth Casson Leighton 2020-02-24 23:59:56 GMT

good call. hm has the khronos group been alerted, it would be good to keep track.

Comment 2 Jacob Lifshay 2020-02-25 00:41:31 GMT

(In reply to Luke Kenneth Casson Leighton from comment #1)
> good call. hm has the khronos group been alerted, it would be good to keep
> track.

I would assume that the Khronos group knows or will know about this because it will end up in the list of OpenGL extensions that they track.