FC3 mediacheck

[Paul Howarth]

On Sun, 2005-07-10 at 23:05 -0500, Reshat Sabiq wrote:
> akonstam at trinity.edu wrote: 
> > On Fri, Nov 12, 2004 at 10:12:17PM -0500, Erik Hemdal wrote:
> >   
> > > > > > md5sum -c MD5SUM
> > > > > > 
> > > > > > I've already indicated this once. After successful MD5SUM check - boot
> > > > > > with 'linux ide=nodma' and then do the MediaCheck.)
> > > > > >           
> > > I think this comment was from Satish about ide=nodma.  Why is that
> > > necessary?  I've encountered the mediacheck failures similarly for the
> > > first time ever.  If the drive operates normally, why do we need nodma
> > > in order to check only disk2 and disk3 of the CD set?  
> > > 
> > > I'm not intending this as disrespectful to anyone; I'm truly curious
> > > about it.  Out of the four install images, all four pass the MD5
> > > checksum test, and two out of four pass the mediacheck.  On my CD
> > > writer, cdrecord reports that the buffer was always adequately filled
> > > and burnfree protection was never needed.  So assuming the integrity of
> > > the media is OK (seems to be, since cdrecord reports no errors and the
> > > CD is readable), I'd suspect a problem with the original ISO image. 
> > > Whether you use DMA or not on your drive doesn't seem to have any
> > > bearing on things....else other I/O would have trouble too.
> > > 
> > > Am I missing something?  
> > > 
> > > Erik
> > > 
> > >     
> > I don't know what you are missing but with some hardware the ide=nodma
> > is necessary for to mediacheck to work and the installation from CD's
> > to work without getting read errors.
> >   
> I encountered the nodma issue when i was upgrading to FC3 last year as
> well. For some time i thought that nodma might be needed on all read
> operations on such hardware, but i'm no longer sure that's the case.
> There might be a corrrelation though between this issue and the fact
> that Linux media players crash on me on one out of about 8 or 10 DVDs.
> Might suggest that there's something wrong with the driver causing
> both issues.

The underlying problem for the mediacheck issue is that the IDE CD-ROM
driver doesn't detect the end of the media correctly, and so reads back
more data that it should, causing the media check to fail. There
shouldn't be any issues handling regular data in normal operation.

Paul.
-- 
Paul Howarth <paul at city-fan.org>