netdev - Re: [PATCH] igb: fix kexec with igb

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Message-Id: <200903082240.26380.rjw@sisk.pl>
Date:	Sun, 8 Mar 2009 22:40:25 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Brandeburg <jesse.brandeburg@...il.com>,
	David Miller <davem@...emloft.net>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	NetDev <netdev@...r.kernel.org>
Subject: Re: [PATCH] igb: fix kexec with igb

On Sunday 08 March 2009, Yinghai Lu wrote:
> Rafael J. Wysocki wrote:
> > On Sunday 08 March 2009, Yinghai Lu wrote:
> >> Rafael J. Wysocki wrote:
> >>> On Saturday 07 March 2009, Yinghai Lu wrote:
> >>>> On Fri, Mar 6, 2009 at 11:18 PM, Jesse Brandeburg
> >>>> <jesse.brandeburg@...il.com> wrote:
> >>>>> On Fri, Mar 6, 2009 at 8:33 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> >>>>>> Impact: could probe igb
> >>>>>>
> >>>>>> Found one system with 82575EB, in the kernel that is kexeced, probe igb
> >>>>>> failed with -2.
> >>>>>>
> >>>>>> it looks like the same behavior happened on forcedeth.
> >>>>>>
> >>>>>> try to check system_state to make sure if put it on D3
> >>>>>>
> >>>>>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> >>>>>>
> >>>>>> ---
> >>>>>>  drivers/net/igb/igb_main.c |   19 ++++++++++++++-----
> >>>>>>  1 file changed, 14 insertions(+), 5 deletions(-)
> >>>>> I see the point of the patch, but I know for a fact that ixgbe when
> >>>>> enabled for MSI-X also doesn't work with kexec.
> >>>>>
> >>>>> so my questions are:
> >>>>> are you going to change every driver?
> >>>> i tend to only change driver that i have related HW.
> >>>>
> >>>>> why can't this be fixed in core kernel code instead?
> >>>> will check it.
> >>>>
> >>>>> Shouldn't pci_enable_device take it out of D3?
> >>>>> Or maybe it should be taken out of D3 immediately if someone tries to
> >>>>> ioremap any of the BARx registers?
> >>>> looks like second kernel can not detect the state any more.
> >>> In fact pci_enable_device() calls pci_set_power_state(dev, PCI_D0) as the first
> >>> thing.  The question is why it doesn't work as expected.
> >> not sure... please check the version for forcedeth that you made.
> >>
> >> commit 3cb5599a84c557c0dd9a19feb63a3788268cf249
> >> Author: Rafael J. Wysocki <rjw@...k.pl>
> >> Date:   Fri Sep 5 14:00:19 2008 -0700
> >>
> >>     forcedeth: fix kexec regression
> >>     
> >>     Fix regression tracked as http://bugzilla.kernel.org/show_bug.cgi?id=11361
> >>     and caused by commit f735a2a1a4f2a0f5cd823ce323e82675990469e2 ("[netdrvr]
> >>     forcedeth: setup wake-on-lan before shutting down") that makes network
> >>     adapters integrated into the NVidia MCP55 chipsets fail to work in kexeced
> >>     kernels.  The problem appears to be that if the adapter is put into D3_hot
> >>     during ->shutdown(), it cannot be brought back into D0 after kexec (ref.
> >>     http://marc.info/?l=linux-kernel&m=121900062814967&w=4).  Therefore, only
> >>     put forcedeth into D3 during ->shutdown() if the system is to be powered
> >>     off.
> > 
> > Thanks, I remember now.
> > 
> > This appears to be quirky hardware, doesn't it?
> > 
> all my systems with ck804 and mcp55 need this trick.
> 
> for igb: one system need this trick, and other doesn't need this trick.
> could BIOS/ACPI difference or the nic option rom difference.
> 
> but for kexec path, we really don't need put pci devices to D3.

Agreed, but pci_set_power_state() may be called for too many different reasons
to be a suitable place for a fix IMO.

Thanks,
Rafael
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