[M] Change in coreboot[main]: mb/qemu-{i440fx,q35}/rom_media.c: add code for writable flash

[Krystian Hebel (Code Review)]

Attention is currently required from: Michał Kopeć, Michał Żygowski, Patrick Rudolph, Paul Menzel, Sergii Dmytruk.

Krystian Hebel has posted comments on this change by Krystian Hebel. ( https://review.coreboot.org/c/coreboot/+/82555?usp=email )

Change subject: mb/qemu-{i440fx,q35}/rom_media.c: add code for writable flash
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Patch Set 5:

(3 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/82555/comment/e6969ffc_73d38479?usp... :
PS4, Line 18: 8
> The default is BOARD_ROMSIZE_KB_16384. […]

Changed in CB:82639. QEMU bails out immediately, but only for `-drive if=pflash`, `-bios` can use up to 16M images.

File src/mainboard/emulation/qemu-i440fx/rom_media.c:

https://review.coreboot.org/c/coreboot/+/82555/comment/fbfa09dc_18be5128?usp... :
PS4, Line 138: uintptr_t
> base is a pointer, no need for cast here

Acknowledged

https://review.coreboot.org/c/coreboot/+/82555/comment/477887e3_29e5d495?usp... :
PS4, Line 158: flash_ops
> Should there be a readat() implementation that is always available?

`mdev_readat` is used for all 3 options, it is copied in line 131 from `mem_rdev_rw_ops`.