Re: [Xen-devel] Console getting disk debug output?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

> 
> > I'm trying to connect to a Xen (1.2) console via a terminal
> > concentrator and, on boot, instead of getting console output
> > I'm getting literally thousands of lines as follows:
> > 
> > hdb: 0x0080 0x000001cb7376
> > [A]
> > hdb: writing: LBAsect=30110710, sectors=128, buffer=0x00253000,
> 
> This is bizarre. 
> 
> Someone has commented out the "#ifdef DEBUG" in
> xen/drivers/ide/ide-disk.c in several places.
> 
> The strange thing is that the changelog suggest this was done 13
> months ago! Why hasn't anyone noticed before?
> 
> We do most of our testing on SCSI, but there are *loads* of
> people using IDE in production environments. Surely this debug
> output hasn't been coming out the whole time without anyone
> noticing? I suspect that something else must have been gating it
> until very recently, but I'm not sure what. I'll investigate.
> 
> In the meantime, remove the comments from ide-disk.c

Amusing! The reason is that until recently we had not run Xen on a
system with an IDE disc using "48-bit LBA mode". The older 28-bit LBA
mode can address up to 137GB discs, but of course now 160GB is the
"knee" of the price-capacity curve (which is where everyone buys their
IDE discs).

So we are just beginning to run Xen on discs of sufficient capacity to
require LBA-48 addressing, which executes hardly-tested code paths in
Xen. Debugging was never turned back off on those paths. :-)

I'll turn the debugging off...

 -- Keir


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