Re: OS X IOKit equivalent for IRP_MN_QUERY_RESOURCE

Re: OS X IOKit equivalent for IRP_MN_QUERY_RESOURCE_REQUIREMENTS?

Subject: Re: OS X IOKit equivalent for IRP_MN_QUERY_RESOURCE_REQUIREMENTS?

From: Jason Seng <email@hidden>

Date: Fri, 11 May 2007 14:12:30 -0700

Delivered-to: email@hidden

Hi Jim,

On May 11, 2007, at 12:04 PM, email@hidden wrote:

------------------------------

Message: 2

Date: Thu, 10 May 2007 17:25:24 -0700

From: Jim Wintermyre <email@hidden>

Subject: Re: OS X IOKit equivalent for

IRP_MN_QUERY_RESOURCE_REQUIREMENTS?

To: email@hidden

Message-ID: <a06210219c269670bba54@[192.168.1.251]>

Content-Type: text/plain; charset="us-ascii" ; format="flowed"

Hmm, no bites, so let me try again. Is there any way in OS X for a

device driver to get a query from the OS about what the OS thinks the

device's resource requirements are, which the driver can then modify

and return to the OS *before* the OS actually allocates those

resources?

PCI devices are probed and resources assigned at boot time, i.e. before the OS loads.

In my case, the hardware on our PCI device says it needs a 128 MB

memory window (which is what shows up in the IO registry for

IODeviceMemory for the device). However, for the way we are using

the device, we don't actually need to use that entire memory window,

so we'd like to tell the OS that we only *really* need, say, 32 MB.

For Open Firmware you could provide an FCode driver that can override the address space size requested by a BAR.

Apparently similar functionality is not available in EFI. :(

Without changing the hardware, if possible. :)

Well, your hardware should request what it actually needs ;)

My Windows counterparts are making fun of me because they can do this

in Windows...

<sigh>

Cheers,

Jason

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