Re: [Qemu-devel] Commit b2a575a1c652 broke i486 support.

[Thomas Huth]

On 30.05.2017 21:05, Rob Landley wrote:
> On 05/29/2017 05:14 AM, Richard W.M. Jones wrote:
>> I see in the disassembly use of cmovne (new in Pentium Pro) and
>> bswap (new in 486).
>> [http://cse.unl.edu/~goddard/Courses/CSCE351/IntelArchitecture/InstructionSetSummary.pdf]
>>
>> The cmovne instruction is generated by the compiler (GCC in my case),
>>
>> The following patch removes the cmovne instruction, so it should work
>> on 486 (although I didn't test it).  It's not possible to remove bswap
>> without surgery on the inline assembler.
> 
> Is there any way to make it just _not_ load the option rom for -cpu 486?
> It ran fine before that thing went in...

Looking at that commit b2a575a1c652 that you've mentioned, it seems like
you could work-around the problem by disabling DMA for the fw_cfg
device. Try something like adding the parameter

 -global fw_cfg.dma_enabled=false

to your command line. If that does not help, try to use an older machine
type, like "-M pc-i440fx-2.5".

 Thomas