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From: | G 3 |
Subject: | Re: [Qemu-ppc] [Qemu-devel] Floating point unit bugs |
Date: | Mon, 8 May 2017 18:09:49 -0400 |
On May 8, 2017, at 5:54 PM, Aurelien Jarno wrote:
On 2017-05-07 17:48, G 3 wrote:I made a diagnostic program for the floating point unit. It will testvarious PowerPC floating point instructions for compatibility with the PowerPC G3 processor. It was tested on a PowerPC G3 and G5 system. The results of the program in qemu-system-ppc were pretty bad. About everyinstruction tested is not implemented correctly.I don't say that qemu-system-ppc is bug free, but this looks suspiciousthat about every instruction is buggy.
I really hope you don't think I'm blaming anyone. I'm only reporting the results of the test.
Have you tried to run your program on a real G3 or G5 system?
Yes. I made sure it ran on a real G3 and G5 system without problem before testing it on QEMU. I suspect the Motorola designed G4 processor will not be compatible. I don't have a working G4 system to verify this unfortunately.
[ snip ]Here is the full test results after running this program in qemu- system-ppcwith a Mac OS 10.4 guest: fadd test failed expected answer: 0x3ff3333333333334 actual answer: 0x8200400000000024 expected fpscr: 0x82064000 actual fpscr: 0x82004000This looks highly suspicious that the actual answer match the expected answer.
You can use this web page to find the decimal value: http:// www6.uniovi.es/~antonio/uned/ieee754/IEEE-754hex64.html
0x3ff3333333333334 = 1.2000000000000002 0x8200400000000024 = -4.8529708162167760e-299 The expected answer and actual answer are very far from each other.
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