rpi5_mailbox.c: wire the VideoCore mailbox message protocol (FABRIC-3.md §IV.3 item 3)
New rpi5_mailbox_get_framebuffer() sends one property-tag request buffer (phys size, virt size, depth, pixel order, virtual offset, allocate-buffer, get-pitch) over the register layout rpi5_dtb.c already discovers, populating an Rpi5FramebufferInfo kept in exact field-for-field sync with uefi.h's FramebufferInfo so console.c/vt100.c/framebuffer.c need no downstream changes once this is wired into a real entry stub. Register offsets (+0x00/+0x18 MBOX0 read/status, +0x20/+0x38 MBOX1 write/status) confirmed against a Pi-5-specific bare-metal reference, independently cross-checked against this codebase's own rpi5_dtb.c translated base address. Caught and fixed a real buffer-overflow bug before compiling: the static request buffer was sized 32 words against an actual 35-word requirement for the 7-tag sequence, recomputed exactly rather than re-estimated; resized to 40 words. Two things flagged as genuinely unverified against real hardware (not guessed past the comment): the allocate-buffer tag's request-size field value, and whether its response address needs classic bus-alias masking on Pi 5 specifically. Compile-only-verified -- no caller yet (that's the still-open entry-stub/DTB constructor items). Verified 3-arch boot to ok>/zuse)ok>. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019YcT3H2PQeyujrzjqS3Var
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Robert Allan James
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Claude Sonnet 5
Claude Sonnet 5
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