[U-Boot] [RFC] fit: include uncompression into fit_image_load

[Simon Goldschmidt]

On Wed, Oct 17, 2018 at 8:54 AM Alexander Graf <agraf at suse.de> wrote:
>
>
>
> On 16.10.18 21:33, Simon Goldschmidt wrote:
> > Currently, only the kernel can be compressed in a FIT image.
> > By moving the uncompression logic to 'fit_image_load()', all types
> > of images can be compressed.
> >
> > This works perfectly for me when using a gzip'ed FPGA image in
> > a FIT image on a cyclone5 board (socrates). Also, a gzip'ed initrd
> > being unzipped by U-Boot (not the kernel) worked.
> >
> > To clean this up, the uncompression function would have to be moved
> > from bootm.c ('bootm_decomp_image()') to a more generic location,
> > but I decided to keep it for now to make the patch easier to read.
> > Because of this setup, the kernel is currently uncompressed twice.
> > which doesn't work...
> >
> > There are, however, some more things to discuss:
> > - The max. size passed to gunzip() (etc.) is not known before, so
> >   we currently configure this to 8 MByte in U-Boot (via
> >   CONFIG_SYS_BOOTM_LEN), which proved too small for my initrd...
> > - CONFIG_SYS_BOOTM_LEN is set to 64 MByte default in SPL, so it's
> >   a different default for SPL than for U-Boot !?!
> > - CONFIG_SYS_BOOTM_LEN seemed to initially be used for kernel
> >   uncompression but is now used as a copy-only limit, too (no unzip)
> > - Uncompression only works if a load address is given, what should
> >   happen if the FIT image does not contain a load address?
> > - The whole memory management around FIT images is a bit messed up
> >   in that memory allocation is a mix of where U-Boot relocates itself
> >   (and which address ranges it used), the load addresses of the FIT
> >   image and the load addresses of the FIT image contents (and sizes).
> >   What's the point here to check CONFIG_SYS_BOOTM_LEN? Maybe it would
> >   be better to keep a memory map of allowed and already used data to
> >   check if we're overwriting things or to get the maximum size passed
> >   to gunzip etc.?
>
> So I can at least give input on the memory map part :).
>
> In efi_loader, we actually do maintain a full system memory map already,
> including allocation functions that give you "safe" allocation
> functionality (allocate somewhere in memory where you know nothing
> overlaps).
>
> Maybe we should move this into a more generic system and reuse it for
> big memory allocations that really don't need to be in the U-Boot
> preallocated regions?

Hmm, inspecting this further, it seems that there is such an allocator
for bootm (using lmb_*() functions and struct lmb). Maybe this should be
better integrated into the fit loading function. I don't know if the
lmb functions
correctly detect overlapping of regions allocated by known addresses though.

Thanks for your thoughts!

Simon