Re: [Qemu-devel] [PATCH] Flush pending AIO on reboot and shutdown.

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Gleb Natapov, le Wed 13 Aug 2008 17:25:58 +0300, a écrit :
> On Wed, Aug 13, 2008 at 03:06:41PM +0100, Samuel Thibault wrote:
> > Gleb Natapov, le Wed 13 Aug 2008 16:59:41 +0300, a écrit :
> > > On Wed, Aug 13, 2008 at 02:46:08PM +0100, Samuel Thibault wrote:
> > > > Gleb Natapov, le Wed 13 Aug 2008 16:23:58 +0300, a écrit :
> > > > > If there is outstanding IDE IO when BIOS starts execution then IDE
> > > > > commands sent by BIOS will interfere with it and will leave IDE
> > > > > subsystem in unpredictable state. This can happen when system reboots
> > > > > unexpectedly without waiting for IO completion. Flushing IO before exit
> > > > > prevents data lose.
> > > > 
> > > > I'm wondering: isn't that what happens with real machines?
> > > > 
> > > With shutdown yes, but why not try harder. With reboot I don't think
> > > that in real HW you can hang IDE interface after reboot ;)
> > 
> > Mmm, I couldn't understand.
> > 
> > With real hardware, if you reboot into the bios the board is not
> > resetted either, and thus the interference is the same.
> > 
> On real hardware if you press reset button

That's when you press the reset button.  When you have a triple fault
the IDE board won't be resetted.

> Currently BOCHS BIOS doesn't check that IDE is busy (it doesn't even
> know that HW is present) and sends overlapping command.

Then fix it.

Samuel