[flashrom] [PATCH 1/8] ichspi: add ICH/PCH flash descriptor decoding via FDOC/FDOD

[Carl-Daniel Hailfinger]

Am 03.09.2011 12:33 schrieb Stefan Tauner:
> On Fri, 02 Sep 2011 21:33:33 +0200
> Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> wrote
>> Am 20.08.2011 12:39 schrieb Stefan Tauner:
>>     
>>> because this patch relies on (compiler) implementation-specific
>>> layouting of bit-fields, it checks for basic compiler support in the
>>> makefile and for correct layout before taking any action on runtime.  
>>>       
>> Checking for presence of bitfield support in the compiler is the way to
>> madness. Next we have to test for C99 capability and other fun stuff.
>> Just assume that bitfields are supported, otherwise compilation will
>> blow up or the runtime checks will catch a miscompilation. That
>> compile-time check (including the #if BITFIELDS) is nacked.
>>     
> well, for now bit-fields are only needed in one place that is seldom
> needed. why break compilation unnecessarily for all other cases too?
>   

Would it really break compilation? AFAICS not.
Bitfield support is available at least in all recent gcc and clang, and
probably other compilers as well. No need to test for that at compile time.


> basically i agree, but since everyone thinks bit-fields break all the
> time i thought it is a good idea to integrate it in the least
> interfering way possible... :)
>   


Bitfields have various implementation-defined aspects which may explode
in your face unless you test for them at runtime, but it is technically
impossible to test those at compile time.


>> […]
>>     
>>> +
>>> +#define RET_OK		0
>>> +#define RET_ERR		-1
>>> +#define RET_WARN	-2
>>> +#define RET_PARAM	-3
>>> +#define RET_OOB		-4
>>>   
>>>       
>> Too generic names.
>>     
> not at all, but they should be moved to wherever we want the generic
> return macros to be eventually ;)
> can we do that and/or introduce the universal values before/with merge
> of this patch?
> some additional FL_ prefix or so would be ok with me.
> i could of course rename them now, and then again, but we should add
> the universal return values soon-ish anyway.
>   

You mean like the various (and partially unmerged) patches which added
definitions like ERROR_PTR and TIMEOUT_ERROR? Much more important than
the name is deciding on which errors we want to handle as separate
return codes and whether a warning should indeed be a return code
different from OK.


>> […]
>>     
>>> diff --git a/ichspi.c b/ichspi.c
>>> index 8b4210e..09af2b3 100644
>>> --- a/ichspi.c
>>> +++ b/ichspi.c
>>> @@ -1190,6 +1197,7 @@ int ich_init_spi(struct pci_dev *dev, uint32_t base, void *rcrb,
>>>  	uint8_t old, new;
>>>  	uint16_t spibar_offset, tmp2;
>>>  	uint32_t tmp;
>>> +	int ichspi_desc = 0;
>>>  
>>>  	switch (ich_generation) {
>>>  	case 7:
>>> @@ -1261,6 +1269,8 @@ int ich_init_spi(struct pci_dev *dev, uint32_t base, void *rcrb,
>>>  			msg_pinfo("WARNING: SPI Configuration Lockdown activated.\n");
>>>  			ichspi_lock = 1;
>>>  		}
>>> +		if (tmp2 & HSFS_FDV)
>>> +			ichspi_desc = 1;
>>>   
>>>       
>> How does FDOVR (or whatever the correct acronym for Flash Descriptor
>> Override is) relate to this?
>>     
> Flash Descriptor Override Pin-Strap Status (FDOPSS).
> it is later called flash descriptor *security* override pin, and this
> hints at its true purpose: overriding the region access rights declared
> in the descriptor.
>
> quote ich8 datasheet description of the respective pin (GPIO33):
> "If sampled low, the Flash Descriptor Security will be overridden. If
> high, the security measures defined in the Flash Descriptor will be in effect."
>   

Excellent, this clears up one FIXME in the ICH code.


> even then the whole descriptor is of interest imo... and this will most
> likely never occur in practice anyway.
>   

A possible use case is allowing reflashing of a dev board with an
additional jumper.

Regards,
Carl-Daniel

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