[SeaBIOS] ohci bulk?

Kevin O'Connor kevin at koconnor.net
Wed Sep 22 14:52:42 CEST 2010

On Wed, Sep 22, 2010 at 06:40:58AM +0200, Peter Stuge wrote:
> Kevin O'Connor wrote:
> > When in 16bit mode, one can only reliably access the first 1Meg of
> > ram.
> Flat real mode?

The BIOS can put the machine in big real mode when it launches the OS,
but it can't expect that it will always be called in big real mode.
The BIOS could attempt to transition to 32bit mode (or big real mode)
in the disk handler, but it may have been called in vm86 mode which
would then effectively cause a crash.  (It also wipes out the hidden
segment registers which may confuse the OS.)  Use of vm86 mode is not
uncommon - freedos does it and so does (I'm told) Linux.


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