[OpenBIOS] [PATCH] More complete PowerPC OpenFirmware emulation -- adding bus-frequency

Mark Cave-Ayland mark.cave-ayland at siriusit.co.uk
Wed Aug 10 13:13:31 CEST 2011

On 09/08/11 22:42, Tarl Neustaedter wrote:

> For what it's worth, Sun systems don't (currently) use a "bus-frequency"
> property. We do have a "stick-frequency" property, which relates the
> "stick" register to real-time nanoseconds, but that's specific to the
> sun4v series of platforms.

Do sun4m systems actually benchmark the CPU within OBP? From Artyom's 
blog for example, it appears that OBP attempts to benchmark the CPU 
since its speed is listed as over 1GHz in QEMU in the Solaris kernel -v 
output which makes me feel that it does.

I think this may be related to some random hangs I see during CPU 
detection in SPARC32 which look like they are caused by an interaction 
between the level 14 timer and the kernel (as changing the values makes 
this more/less likely). In other words, I think that benchmarking the 
CPU during startup and writing the estimated frequency into the device 
tree may fix interesting issues caused by calling get_hrtime() within a 
tight loop during emulation.



Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs

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