Re: [PATCH v5] FIT: Parse `load` and `entry` addresses.

[Christian Mauderer <christian.mauderer@embedded-brains.de>]

Hello Sascha,

On 12/08/2020 12:08, Sascha Hauer wrote:
> On Wed, Aug 12, 2020 at 08:47:47AM +0200, Christian Mauderer wrote:
>> Hello Sascha,
>>
>> thanks for the review.
>>
>> On 11/08/2020 09:57, Sascha Hauer wrote:
>>> Hi Christian,
>>>
>>> On Wed, Jul 15, 2020 at 11:26:56AM +0200, Christian Mauderer wrote:
>>>> According to the U-Boot documentation for the FIT file format, the load
>>>> and entry have to be allways defined for a "kernel" or "standalone".
>>>> But Barebox ignored the parameters. That changes with this patch.
>>>>
>>>> For backward compatibility the default address is still used for images
>>>> without `load` or `entry`.
>>>>
>>>> Signed-off-by: Christian Mauderer <christian.mauderer@embedded-brains.de>
>>>> ---
>>>>  common/blspec.c     |  1 +
>>>>  common/boot.c       |  1 +
>>>>  common/bootm.c      | 24 ++++++++++-
>>>>  common/image-fit.c  | 97 ++++++++++++++++++++++++++++++++++++++-------
>>>>  include/image-fit.h |  3 ++
>>>>  5 files changed, 110 insertions(+), 16 deletions(-)
>>>>
>>>> diff --git a/common/blspec.c b/common/blspec.c
>>>> index 7fb62d310..050aed26a 100644
>>>> --- a/common/blspec.c
>>>> +++ b/common/blspec.c
>>>> @@ -142,6 +142,7 @@ static int blspec_boot(struct bootentry *be, int verbose, int dryrun)
>>>>  	globalvar_set_match("bootm.initrd", "");
>>>>  
>>>>  	bootm_data_init_defaults(&data);
>>>> +	data.os_entry = 0;
>>>
>>> You set data.os_entry explicitly to 0 here...
>>>
>>>>  
>>>>  	devicetree = blspec_entry_var_get(entry, "devicetree");
>>>>  	initrd = blspec_entry_var_get(entry, "initrd");
>>>> diff --git a/common/boot.c b/common/boot.c
>>>> index dcbe5cc2e..93ac1612d 100644
>>>> --- a/common/boot.c
>>>> +++ b/common/boot.c
>>>> @@ -104,6 +104,7 @@ static int bootscript_boot(struct bootentry *entry, int verbose, int dryrun)
>>>>  
>>>>  	bootm_data_init_defaults(&data);
>>>>  
>>>> +	data.os_entry = 0;
>>>
>>> ...and here. Why is this done? I think these should be left to the
>>> default UIMAGE_SOME_ADDRESS. In the end the kernels bootet from blspec
>>> or a boot script could be a FIT image as well.
>>>
>>
>> You maybe noted that I added the default of UIMAGE_SOME_ADDRESS to
>> bootm_data_init_defaults. I think that it is a sensible default and it
>> was useful for adding the command.
> 
> Yes.
> 
>>
>> Before I did that, in these two cases the value for os_entry was
>> initialized with 0. With setting it explicitly to 0 I wanted to make
>> sure that the behavior doesn't change.
>>
>> But you are right: I added a check for that in bootm_boot later. I just
>> checked again: There is no case where the os_entry is used in between.
>> So these two should be not unnecessary.
>>
>> I'll remove it in a v6 of the patch.
> 
> Ok, thanks
> 
>>
>>>> +int fit_get_image_address(struct fit_handle *handle, void *configuration,
>>>> +			  const char *name, const char *property,
>>>> +			  unsigned long *address)
>>>> +{
>>>> +	struct device_node *image;
>>>> +	const char *unit = name;
>>>> +	int ret;
>>>> +
>>>> +	if (!address || !property || !name)
>>>> +		return -EINVAL;
>>>> +
>>>> +	ret = fit_get_image(handle, configuration, &unit, &image);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	pr_info("%s/%s: ", image->full_name, property);
>>>> +
>>>> +	ret = fit_get_address(image, property, address);
>>>> +	if (ret < 0)
>>>> +		pr_cont("<not found>\n");
>>>> +	else
>>>> +		pr_cont("0x%lx\n", *address);
>>>
>>> pr_cont() doesn't work well in barebox and should be avoided.
>>
>> I wasn't aware of that. In one of the earlier versions of the patch it
>> was suggested to print that info. I'll find another solution or remove it.
>>
>>>
>>> Also I think this function shouldn't print anything, the caller should
>>> if it wishes to.
>>
>> I had the impression that most of the functions print the information
>> themselves. For example fit_open_image prints a lot of information about
>> the image. fit_find_compatible_unit (which is used in
>> fit_open_configuration) prints that it found a matching unit.
>>
>> It is a bit unclear when it would be OK for a function to print anything
>> and when not.
> 
> Indeed it is unclear :)
> 
> Generally it's nice when a function prints some information, but here I
> had the feeling that this function might get called in places where we
> don't want to print anything. It doesn't matter much at the moment since
> this function is called in this single place only anyway.
> 
>> But I can move the print to bootm_boot where the function
>> is called. Or would you prefer that it is removed completely? I'm not
>> sure whether bootm_boot prints that information later?
> 
> bootm will print later where it puts the kernel, but not where it got
> the address from, so I think printing it here is valuable.
> 
> I just noticed that with your patch bootm refuses to boot FIT images
> that don't have load and entry address explicitly given, right? That
> shouldn't be the case.

Also according to the spec for a FIT image the load and entry are
mandatory, my intention was to implement it backward compatible. The
values should be only parsed if no one set them earlier. And if nothing
is found, the default value of UIMAGE_INVALID_ADDRESS (for address) and
0 (for entry) should be used. But I'll check and test that before I send
a v6.

Best regards

Christian

> 
> Sascha
> 

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