[SeaBIOS] Booting from USB thumbdrives, older drives boot, newer drives don't.

[Dave Frodin]

----- Original Message -----
> From: "Paolo Bonzini" <pbonzini at redhat.com>
> To: "Kevin O'Connor" <kevin at koconnor.net>
> Cc: "Dave Frodin" <dave at camp.se-eng.com>, seabios at seabios.org
> Sent: Monday, March 5, 2012 1:17:08 AM
> Subject: Re: Booting from USB thumbdrives, older drives boot, newer drives don't.
> 
> Il 04/03/2012 19:49, Kevin O'Connor ha scritto:
> >> > The sg_modes command has a "-a" option to dump out all of the
> >> > supported page codes
> >> >    - it reports that none of the thumbdrives (tested 9) support
> >> >    page code = 4
> >> >    - it reports that most of the thumbdrives (tested 9) support
> >> >    page code = 5
> >> >    - it commented that page code 5 is obsolete
> > Thanks Dave.  I appreciate your detailed analysis.
> > 
> > The call to cdb_mode_sense_geom() was only recently added.  I'm
> > inclined to just remove the call.  Paolo, is there a use case where
> > having the "physical" chs info is important?  SeaBIOS should
> > generate
> > good "virtual" chs info regardless, and the underlying "physical"
> > info
> > is only exported in a couple of places.
> 
> MS-DOS doesn't boot if you do not export the physical chs.  I can
> remove
> it, but it was the best testcase I had for SCSI support.
> 
> The simplest solution seems to be to look for page 4 support in page
> 0x3f.

Except that none of the 12 devices I've tested support page 4.
There's also a good chance that some of the devices could generate the
stall on the page 3f request. That's what led us to thinking we should
leave the page 4 query in and just add support to clear the stall. 

> 
> Paolo
> 
>