X-Gene: Unhandled fault: synchronous external abort in pci_generic_config_read32

[Duc Dang]

On Mon, Jul 27, 2015 at 4:36 AM, Catalin Marinas
<catalin.marinas at arm.com> wrote:
> On Fri, Jul 24, 2015 at 05:05:19PM -0700, Duc Dang wrote:
>> On Fri, Jul 24, 2015 at 3:42 PM, Bjorn Helgaas <bhelgaas at google.com> wrote:
>> > I regularly see faults like this on an APM X-Gene:
>> >
>> >   U-Boot 2013.04-mustang_sw_1.14.14 (Dec 16 2014 - 15:59:33)
>> >   CPU0: APM ARM 64-bit Potenza Rev B0 2400MHz PCP 2400MHz
>> >        32 KB ICACHE, 32 KB DCACHE
>> >        SOC 2000MHz IOBAXI 400MHz AXI 250MHz AHB 200MHz GFC 125MHz
>> >   ...
>> >   Unhandled fault: synchronous external abort (0x96000010) at 0xffffff8000110034
>
> That's generated by an external device (PCIe root complex, card etc.)
> and some mis-configured CPU setting.
>
>> >   Internal error: : 96000010 [#1] SMP
>> >   Modules linked in:
>> >   CPU: 0 PID: 3723 Comm: ... 4.1.0-smp-DEV #3
>> >   Hardware name: APM X-Gene Mustang board (DT)
>> >   task: ffffffc7dc1a4140 ti: ffffffc7dc118000 task.ti: ffffffc7dc118000
>> >   PC is at pci_generic_config_read32+0x4c/0xb8
>> >   LR is at pci_generic_config_read32+0x40/0xb8
>> >   pc : [<ffffffc00033b90c>] lr : [<ffffffc00033b900>] pstate: 600001c5
>> >   ...
>> >   Call trace:
>> >   [<ffffffc00033b90c>] pci_generic_config_read32+0x4c/0xb8
>> >   [<ffffffc00033bf58>] pci_user_read_config_byte+0x60/0xc4
>> >   [<ffffffc0003496a8>] pci_read_config+0x15c/0x238
>> >   [<ffffffc0002393b4>] sysfs_kf_bin_read+0x68/0xa0
>> >   [<ffffffc00023896c>] kernfs_fop_read+0x9c/0x1ac
>> >   [<ffffffc0001c361c>] __vfs_read+0x44/0x128
>> >   [<ffffffc0001c3e28>] vfs_read+0x84/0x144
>> >   [<ffffffc0001c4764>] SyS_read+0x50/0xb0
>>
>> The log shows kernel gets an exception when trying to access Mellanox
>> card configuration space. This is usually due to suboptimal PCIe
>> SerDes parameters are using in your board, which will cause bad link
>> quality.
>
> I would have hoped that "suboptimal" means that it still works, albeit
> not fully optimal ;).

Yes, it should still work, but you may see crashes occasionally due to
link quality.

>
>> The PCIe SerDes programming is done in U-Boot, so I suggest you do a
>> U-Boot upgrade to our latest X-Gene U-Boot release.
>>
>> In order to access latest X-Gene U-Boot release, please use APM
>> official support channel:
>> https://myapm.apm.com
>>
>> Please register an account at myapm.apm.com if you don't have one
>> using following link:
>> https://myapm.apm.com/user/register
>
> Isn't the latest U-Boot source for X-Gene publicly available anywhere?
> It's GPL code anyway, so it shouldn't have proprietary code to require
> registration, click-through agreements.

APM X-Gene U-Boot isn't available publicly yet. Though, if this is
required, we can make a public GIT which will be hosted with APM
server.

As of now, customer who has a board from APM will have to use MyAPM to
get U-Boot source and binary.
>
> --
> Catalin



-- 
Regards,
Duc Dang.