Nouveau - Nov 2014 - Is it necessary to parse the VBIOS init table when executable is false?

Hello everyone,

The code is at /core/subdev/bios/init.c.
When the executable is 0,these functions that parse the VBIOS init table seems
to do nothing except the parsing. And in my opinion,init_exec_force does
nothing,too!

Then I tried to test it on my computer,when the VBIOS parser tries to change a
MMIO register or call a function of struct nouveau_devinit (such as
devinit->pll_set,etc.),it will print a message into the kernel log. However,I
cannot see any message about this in the kernel log!

Finally,I decided to just return when executable is zero. Then I found out the
driver also works perfectly.

So I asked the question here,thanks for your help.

On 20 Nov 2014 01:31, "李金华" <goodqt at outlook.com>
wrote:
>
> Hello everyone,
>
> The code is at /core/subdev/bios/init.c.
> When the executable is 0,these functions that parse the VBIOS init table
seems to do nothing except the parsing.
Correct.  We do not handle every opcode, only the ones that have been
observed so far.  The purpose is to be able to test whether we will be able
to fully execute the table, to avoid failing in a critical path (such as
resume from suspend) where we can't recover.

Ben.

And in my opinion,init_exec_force does nothing,too!
>
> Then I tried to test it on my computer,when the VBIOS parser tries to
change a MMIO register or call a function of struct nouveau_devinit (such
as devinit->pll_set,etc.),it will print a message into the kernel log.
However,I cannot see any message about this in the kernel
log!
>
> Finally,I decided to just return when executable is zero. Then I found
out the driver also works perfectly.
>
> So I asked the question here,thanks for your help.
> _______________________________________________
> Nouveau mailing list
> Nouveau at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/nouveau
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On Wed, Nov 19, 2014 at 2:42 PM, Ben Skeggs <skeggsb at gmail.com>
wrote:
> On 20 Nov 2014 01:31, "李金华" <goodqt at outlook.com> wrote:
>>
>> Hello everyone,
>>
>> The code is at /core/subdev/bios/init.c.
>> When the executable is 0,these functions that parse the VBIOS init
table
>> seems to do nothing except the parsing.
> Correct.  We do not handle every opcode, only the ones that have been
> observed so far.  The purpose is to be able to test whether we will be able
> to fully execute the table, to avoid failing in a critical path (such as
> resume from suspend) where we can't recover.
It also serves as a nice litmus test as to whether we have the right
VBIOS, since we also execute various bits during output configuration,
reclocking, and probably other things I'm not thinking of.

Most of the time, especially with older cards, the reason this would
be failing is because it's reading the VBIOS from the wrong place
(like PCIROM) and it contains the wrong data.

  -ilia