From: Larry Finger <Larry.Finger@lwfinger.net>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: "linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>
Subject: Re: Problem booting a PowerBook G4 Aluminum after commit cd08f109 with CONFIG_VMAP_STACK=y
Date: Tue, 11 Feb 2020 10:06:39 -0600 [thread overview]
Message-ID: <608a1a18-a0ed-2059-bfbc-081c9ef1bfd8@lwfinger.net> (raw)
In-Reply-To: <f35ea4e6-7c54-6acc-7d91-3a6eea56133c@c-s.fr>
On 2/11/20 12:55 AM, Christophe Leroy wrote:
>
>
> Le 10/02/2020 à 13:55, Larry Finger a écrit :
>> On 2/9/20 12:19 PM, Christophe Leroy wrote:
>>> Do you have CONFIG_TRACE_IRQFLAGS in your config ?
>>> If so, can you try the patch below ?
>>>
>>> https://patchwork.ozlabs.org/patch/1235081/
>>>
>>> Otherwise, can you send me your .config and tell me exactly where it stops
>>> during the boot.
>>
>> Christophe,
>>
>> That patch did not work. My .config is attached.
>>
>> It does boot if CONFIG_VMAP_STACK is not set.
>>
>> The console display ends with the "DMA ranges" output. A screen shot is also
>> appended.
>>
>> Larry
>>
>
> Hi,
>
> I tried your config under QEMU, it works.
>
> In fact your console display is looping on itself, it ends at "printk:
> bootconsole [udbg0] disabled".
>
> Looks like you get stuck at the time of switching to graphic mode. Need to
> understand why.
I'm not surprised that a real G4 differs from QEMU. For one thing, the real
hardware uses i2c to connect to the graphics hardware.
I realized that the screen was not scrolling and output was missing. To see what
was missed, I added a call to btext_clearscreen(). As you noted, it ends at the
bootconsole disabled statement.
As I could not find any console output after that point, I then turned off the
bootconsole disable. I realize this action may cause a different problem, but in
this configuration, the computer hit a BUG Unable to handle kernel data access
at 0x007a84fc. The faulting instruction address was 0x00013674. Those addresses
look like physical, not virtual, addresses.
I then added pr_info statements to bracket the failure. In file
drivers/video/fbdev/core/fb_ddc.c, the code reaches line 66, which is
algo_data->setsda(algo_data->data, 1);
Both pointers seem OK with algo_data = 0xeedfb4bc, and algo_data->data =
0xeedb25c. The code faults before returning. I then annotated that callback
routine radeon_gpio_setsda(), and found that execution is OK to the end of the
routine, but the fault happens on the return from this routine as though the
stack were corrupted.
I will be busy for about 8 hours, but if you can think of any debugging I can do
on this routine, please let me know.
Thanks,
Larry
next prev parent reply other threads:[~2020-02-11 16:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <f7565b89-c8b2-d2e7-929e-4b1abf72fc63@lwfinger.net>
[not found] ` <159ed5d8-376b-1642-fb4b-01406d671cf1@c-s.fr>
[not found] ` <6a1802b8-c6a7-d091-1036-689e089b786f@lwfinger.net>
2020-02-11 6:55 ` Problem booting a PowerBook G4 Aluminum after commit cd08f109 with CONFIG_VMAP_STACK=y Christophe Leroy
2020-02-11 16:06 ` Larry Finger [this message]
2020-02-11 19:23 ` Christophe Leroy
[not found] ` <1787b507-dfbf-7801-f7d4-a1547e9bd588@lwfinger.net>
2020-02-13 11:23 ` Christophe Leroy
[not found] ` <7f63e8a8-95c5-eeca-dc79-3c13f4d98d39@lwfinger.net>
2020-02-13 14:43 ` RESEND: " Christophe Leroy
2020-02-13 23:09 ` Larry Finger
2020-02-14 6:24 ` Christophe Leroy
2020-02-14 11:02 ` Christophe Leroy
2020-02-14 18:20 ` Larry Finger
2020-02-14 18:24 ` Larry Finger
2020-02-14 19:35 ` Christophe Leroy
2020-02-15 2:42 ` Larry Finger
2020-02-15 7:55 ` Christophe Leroy
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