[PATCH 02/15] vbe: Split out reading a FIT into a common file

[Simon Glass]

Hi Tom,

On Sat, 11 Jan 2025 at 15:54, Tom Rini <trini at konsulko.com> wrote:
>
> On Thu, Jan 09, 2025 at 05:29:57AM -0700, Simon Glass wrote:
>
> > Loading a FIT is useful for other VBE methods, such as ABrec. Create a
> > new function to handling reading it.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
>
> This causes a bunch of growth:
>             a3y17lte       : all +1328 text +1328
>                u-boot: add: 8/0, grow: 1/0 bytes: 1328/0 (1328)
>                  function                                   old     new   delta
>                  blkcache_fill                                -     332    +332
>                  blkcache_read                                -     240    +240
>                  blk_read                                     -     188    +188
>                  vbe_read_nvdata                              -     156    +156
>                  vbe_read_version                             -     140    +140
>                  vbe_get_blk                                  -     100    +100
>                  simple_read_nvdata                           -      96     +96
>                  crc8                                         -      72     +72
>                  vbe_simple_read_state                      108     112      +4
>
> Which is unexpected for just moving code around that's not newly used.

I hadn't noticed that on the boards I was trying, so thank you for spotting it.

This is because it now uses blk_read() instead of blk_dread(), so if
BLOCK_CACHE is enabled, it will use the block cache. We could disable
BLOCK_CACHE on those boards perhaps? It is a speed optimisation so
shouldn't be used by boards which care about code size.

> And even when it's just a move it's still growing:
>             xilinx_zynqmp_virt: all +128 bss -72 text +200
>                u-boot: add: 4/0, grow: 0/-1 bytes: 540/-340 (200)
>                  function                                   old     new   delta
>                  vbe_read_nvdata                              -     156    +156
>                  vbe_get_blk                                  -     148    +148
>                  vbe_read_version                             -     140    +140
>                  simple_read_nvdata                           -      96     +96
>                  vbe_simple_read_state                      452     112    -340

Unfortunately this one is hard to fix. As you know, whenever you take
code from a single module and put it into another, the compiler cannot
optimise away the function-call overhead. I'll note that there is no
increase when LTO is used, e.g. with xilinx_versal_net_mini_qspi

So let me know what you think.

Regards,
Simon