Re: [PATCH] Hamachi not doing pci_enable before reading resources

From: Richard B. Johnson (
Date: Wed Feb 07 2001 - 14:50:57 EST

On Wed, 7 Feb 2001 wrote:

> Hi Alan,
> Another driver not doing pci_enable_device() early enough.
> Dave.

A PCI device does not and should not be enabled to probe for resources!
It is only devices that have BIOS that require the device to be enabled
for memory I/O prior to downloading the BIOS into RAM. The BARs are
read/writable (and are required to be), even when the Mem/I/O bits
in the cmd/status register are clear.

This is a required condition! You certainly don't want to write all
ones to a decode (to find the resource length) of a live, on-line chip!
If the chip hickups (think network chips connected to networks, on a
warm-boot), you will trash lots of stuff in memory.

It looks as though you are "fixing" drivers that are not broken and,
in fact, are trying to do the right thing. Maybe the PCI code in the
kernel is preventing access to resources unless the device has been
enabled??? If so, it's broken and should be fixed, instead of all
the drivers.

Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

"Memory is like gasoline. You use it up when you are running. Of
course you get it all back when you reboot..."; Actual explanation
obtained from the Micro$oft help desk.

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