Re: [PATCH 2/2] bootm: add support for booting compressed images

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 26.05.21 11:58, Lucas Stach wrote:
> Am Mittwoch, dem 26.05.2021 um 11:41 +0200 schrieb Ahmad Fatoum:
>> On 26.05.21 11:39, Lucas Stach wrote:
>>> Hi Ahmad,
>>>
>>> Am Mittwoch, dem 26.05.2021 um 11:17 +0200 schrieb Ahmad Fatoum:
>>>> Hello Lucas,
>>>>
>>>> On 25.05.21 20:37, Lucas Stach wrote:
>>>>> ARM64 does not have a self extracting image format, but relies on the image
>>>>> being externally compressed with one of the standard compression algorithms.
>>>>>
>>>>> Add support for decompressing the bootm OS image. It is added in common
>>>>> code as it may also be useful for other images/architectures.
>>>>>
>>>>> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
>>>>> ---
>>>>>  common/bootm.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>  1 file changed, 92 insertions(+)
>>>>>
>>>>> diff --git a/common/bootm.c b/common/bootm.c
>>>>> index 092116beb94a..2bfb5cb01593 100644
>>>>> --- a/common/bootm.c
>>>>> +++ b/common/bootm.c
>>>>> @@ -12,6 +12,7 @@
>>>>>  #include <environment.h>
>>>>>  #include <linux/stat.h>
>>>>>  #include <magicvar.h>
>>>>> +#include <uncompress.h>
>>>>>  
>>>>>  static LIST_HEAD(handler_list);
>>>>>  
>>>>> @@ -808,6 +809,85 @@ err_out:
>>>>>  	return ret;
>>>>>  }
>>>>>  
>>>>> +static int do_bootm_compressed(struct image_data *img_data)
>>>>> +{
>>>>> +	struct bootm_data bootm_data = {
>>>>> +		.oftree_file = img_data->oftree_file,
>>>>> +		.initrd_file = img_data->initrd_file,
>>>>> +		.tee_file = img_data->tee_file,
>>>>> +		.verbose = img_data->verbose,
>>>>> +		.verify = img_data->verify,
>>>>> +		.force = img_data->force,
>>>>> +		.dryrun = img_data->dryrun,
>>>>> +		.initrd_address = img_data->initrd_address,
>>>>> +		.os_address = img_data->os_address,
>>>>
>>>> I am wondering whether it makes sense to directly extract
>>>> to os_address to avoid the extra copy. Depending on the subsequent
>>>> bootm handler, the image may still need to be relocated, but if
>>>> we choose a generous alignment here, the copy later on could
>>>> be avoided.
>>>
>>> For the common case where we let Barebox/the bootm image handler decide
>>> where to put the OS image, we don't know this address yet when
>>> decompressing the image here. I don't think it makes sense to optimize
>>> the special case where the OS address is already known.
>>
>> I see. A debug print for higher verbosity levels, just before invoking
>> bootm_boot would be nice, so it's easy to find out how long the
>> extraction took.
> 
> Actually due to the way this is implemented as nested bootm you kind of
> get this naturally. The output when booting a compressed image looks
> like this:
> 
> blspec: booting someboard from somewhere
> Loading LZO compressed 'somewhere/Image.lzo'
> Loading ARM aarch64 Linux image '/tmp/bootm-compressed-6504dc00'
> Loading devicetree from 'somewhere/someboard.dtb'

Great! :-)

> 
> Regards,
> Lucas
> 
> 

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