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Re: [Qemu-devel] [PATCH] USB 2.0 EHCI emulation

From: Paul Brook
Subject: Re: [Qemu-devel] [PATCH] USB 2.0 EHCI emulation
Date: Tue, 8 Jan 2008 01:30:02 +0000
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> -The host kernel was configured with dynamic tick & hi-res timers, to
> allow the desired timer resolution. USB 2.0 microframe is 125usec.

Requiring a 8kHz timer is a non-starter.

The 100kHz "retry" timer is even more bogus. 

Qemu isn't capable of this kind of realtime response. You need to figure out 
an implementation that doesn't require extremely fine grained timers. In 
paractice you're unlikely to get better than 10ms timer resolution, and 100ms 
latency isn't that uncommon.


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