Re: [Fastboot] Re: Announce: dumpfs v0.01 - common RAS output API

Eric W. Biederman
2004-07-29T15:54:12Z

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> On Iau, 2004-07-29 at 02:12, Eric W. Biederman wrote:
> > Or those devices that hang the machine when you clear it.
>
> There are none. Its required by the PCI spec and used by BIOS vendors
> during the boot sequence. So its a *tested* approach.

Enabling is required. Clearing is not. The particular instance I was
thinking of was disabling memory access and leaving I/O enabled.

> > And there is the fact that the pci configuration access methods
> > are frequently BIOS calls.
>
> You will be running bios code on some systems every time you read
> the cmos clock, every time you touch pci config space, every time
> you hit a key, even in your new kernel boot up path - whats your
> point

Only that in many instances BIOS code can do things we don't expect.
And when we start out with the machine in an unknown state the
risk is worse.

> > So I do see just clearing the master bit on each PCI devices to
> > as dangerous as calling the shutdown methods.
>
> Then we violently disagree

yes.

Eric