On 04.03.2016 11:55, Lorenzo Pieralisi wrote:
On Thu, Mar 03, 2016 at 09:24:56AM -0500, Sinan Kaya wrote:
>On 3/3/2016 6:23 AM, Lorenzo Pieralisi wrote:
> >x86 and IA64 claim PCI resources on boot and live with that (well, minus
> >the gazillions x86 pci= parameters that change the PCI resources assignment
> >one way or another), comments very welcome in particular on the pci=realloc
> >option and its usage.
>
>I have been working with Linux PCIe over 3 years. I never used
>pci=realloc argument.
>
>The v5 series minus [PATCH V5 11/15] drivers: pci: add generic code to
>claim bus resources is working just fine and is ready to go upstream
>in my opinion. It passed my internal testing with different types of
>endpoints.
>
>The inclusion of this patch is now requiring everybody to add
>pci=realloc argument otherwise the resources assigned by the UEFI BIOS
>are not working.
>
>I think there is still some work to be done in this patch and is too
>early to be included into the series. It is blocking progress of the
>series which is sitting on review over 1 year already.
First off, I think that's specious, patch 11 is not blocking anything,
if you and Tomasz want to drop it go ahead and take responsibility
of the consequences.
I am not saying patch 11 is perfect, it is there to review, if you
spot bugs point them out.
If you are interested and willing to make an effort to understand why I
asked Tomasz to integrate it, a bit of background here:
http://permalink.gmane.org/gmane.linux.kernel.pci/44830
If we want to drop patch 11, we are going to discard whatever FW
set-up at FW/OS hand-off and reassign everything. Want to do it ?
Go ahead.
I wrote it in my previous email, probably it was not clear, so, here we
go again.
If we want to at least consider the FW PCI configuration at FW/OS
handoff, we should read the PCI bridge apertures and claim them, when
that fails reassign the corresponding PCI bus hierarchy (which means
releasing the bridge resources and downstream devices and reassign
them), that's what pci=realloc does.
I think that it is a command line option since it has to be a choice,
ie overriding FW set-up should be an option, not a default.
Patch 11 does what x86 does in arch code arch/x86/pci/i386.c,
pcibios_resource_survey()
and that works for them (of course, minus quirks that do exist).
I could integrate the code implementing pci=realloc in patch 11 so
that we realloc by default all resources claimed that failed (which
means that bridges are resized accordingly and you won't be forced
to use pci=realloc on command line).
I agree with Lorenzo. Just because v3 works it does not mean we want to
go this way. Also, I think we should realloc all resources claimed that
failed, w/o need to use pci=realloc on command line.
Tomasz
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