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

[Lucas Stach]

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 at 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.

Regards,
Lucas