Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1469222

Re: x86/PCI: Scan all functions during probing

Show all headers | View raw

On Thu, 18 Aug 2016, Bjorn Helgaas wrote:
> I looked up the spec: PCI (not PCIe) r3.0, sec 3.2.2.3.4, says:
> 
>   A single-function device may optionally respond to all function
>   numbers as the same function or may ... respond only to function 0
>   and not respond to the other function numbers.
> 
> I'm concerned that a single-function device that responds to all
> function numbers might break with this patch.
> 
>   [multi-function devices] are also required to always implement
>   function 0 in the device.
> 
> Here's the reason we can advance by 8 in the "Go find them" loop.
> 
>   If a single function device is detected (i.e., bit 7 in the Header
>   Type register of function 0 is 0), no more functions for that Device
>   Number will be checked.  If a multi-function device is detected
>   (i.e., bit 7 in the Header Type register of function 0 is 1), then
>   all remaining Function Numbers will be checked.
> 
> This patch does the opposite of what the first sentence recommends.

Fair enough. We'll need to find a way to deal with that in jailhouse then.

Thanks,

	tglx

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: x86/PCI: Scan all functions during probing Bjorn Helgaas <helgaas@kernel.org> - 2016-08-19 03:30 +0200
  Re: x86/PCI: Scan all functions during probing Thomas Gleixner <tglx@linutronix.de> - 2016-08-24 10:50 +0200
    Re: x86/PCI: Scan all functions during probing Jan Kiszka <jan.kiszka@siemens.com> - 2016-08-24 13:20 +0200
      Re: x86/PCI: Scan all functions during probing Thomas Gleixner <tglx@linutronix.de> - 2016-08-24 19:30 +0200

csiph-web