5.4-RELEASE amd64: Panic isadma_start : bad bounce buffer

Doug White dwhite at gumbysoft.com
Sat May 14 21:23:15 PDT 2005

On Sat, 14 May 2005, Steven Hartland wrote:

> Thanks for the confirmation there Doug at least I have a workaround :)

As another workaround, add this to loader.conf and reboot:


This uses the old contigmalloc algorithm which may be more successful as
allocating the bounce buffer area.

>     Steve
> ----- Original Message -----
> From: "Doug White" <dwhite at gumbysoft.com>
> >
> > This is a known bug; floppy drives don't work on amd64 since the ISA DMA
> > buffer gets allocated above 16MB.  I don't know if this is something that
> > needs to be handled by busdma.
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Doug White                    |  FreeBSD: The Power to Serve
dwhite at gumbysoft.com          |  www.FreeBSD.org

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