Messages in this thread | | | Date | Thu, 04 May 2006 21:49:53 +0200 | From | Arjan van de Ven <> | Subject | Re: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access |
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Bjorn Helgaas wrote: > On Thursday 04 May 2006 13:11, Arjan van de Ven wrote: >> Bjorn Helgaas wrote: >>> On Saturday 29 April 2006 03:04, Dave Airlie wrote: >>>>> This patch adds an "enable" sysfs attribute to each PCI device. When read it >>>>> shows the "enabled-ness" of the device, but you can write a "0" into it to >>>>> disable a device, and a "1" to enable it. >>>>> >>>>> This later is needed for X and other cases where userspace wants to enable >>>>> the BARs on a device (typical example: to run the video bios on a secundary >>>>> head). Right now X does all this "by hand" via bitbanging, that's just evil. >>>>> This allows X to no longer do that but to just let the kernel do this. >>> I'm all in favor of cleaning up X. But making the X code prettier without >>> changing the underlying issues of claiming and sharing resources doesn't >>> help much. In fact, I suspect the ultimate plan for X does not involve >>> an "enable" attribute in sysfs, so this may just introduce ABI cruft that >>> will be difficult to remove later. >> it goes well beyond X. Things like vbetool need this too to get to the content >> of the rom for example. There are several other such cases... > > There's already a "rom" file in sysfs. Could vbetool and friends > use that?
not unless the device is enabled.
> How do vbetool and X coordinate their usage of "enable"?
Just never disable :)
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