On 19.10.2018 05:25, Simon Glass wrote:
Hi Simon,
On 17 October 2018 at 03:41, Simon Goldschmidt
<simon.k.r.goldschm...@gmail.com> wrote:
On Wed, Oct 17, 2018 at 8:54 AM Alexander Graf <ag...@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...
We need the uncompressed size. If the legacy header doesn't have, stop
using it and use FIT?
Some compression formats include that in a header I think. But we
should record it in the U-Boot header.
OK, we could embed this information into the FIT by extracting in
'mkimage'? That way, we know the uncompressed size...
- CONFIG_SYS_BOOTM_LEN is set to 64 MByte default in SPL, so it's
a different default for SPL than for U-Boot !?!
Ick
- CONFIG_SYS_BOOTM_LEN seemed to initially be used for kernel
uncompression but is now used as a copy-only limit, too (no unzip)
Yes.
Why do we need an extra limit for uncompressed copy-only? Both load
address and size are known from the FIT.
- Uncompression only works if a load address is given, what should
happen if the FIT image does not contain a load address?
Fail.
- 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.?
See lmb
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!
Yes lmb is the right mechanism and I think it checks for overlap.
That didn't work for all overlap checks for me. I'll dig into it to see
what's missing for me.
Simon
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