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Frédéric Desbiens
ea91beae42
#613 exercised the FIQ nesting routines on the FVP. What the model could not show is whether a real GIC-600 routes Group 0 to FIQ the same way, which is the reason to run it here. It does, and the counts match the model exactly. The Group 0 support ports across unchanged: IGRPEN0 and BPR0 on the CPU interface, Group 0 in the distributor, gicv3_enable_sgi_group0, gicv3_send_sgi_group0 through ICC_SGI0R, and the separate Group 0 acknowledge and end-of-interrupt pair. entry.S routes the EL1 FIQ vector into _tx_thread_fiq_context_save with the acknowledge before nesting starts, and leaves FIQ unmasked on the drop to EL1 when FIQ support is compiled in, for the same reason as on the FVP: tx_thread_stack_build only clears a thread's F bit in that configuration. One structural difference from the FVP cost a link. This example reports faults through FAULT_TAIL rather than FAULT_REPORT, so the vector table needed a new el1_fiq_entry label that falls back to fault_el1_fiq. Placing that label inside the TX_R52_USE_THREADX_IRQ guard broke s32z280_boot.elf, which does not define it: the vector reference is unconditional, so the label has to be too. It now sits outside the guard and carries its own, the same shape the demo_m2 link break in #613 forced on the FVP side. Verified on S32Z280 silicon: F1 FIQ delivered and dispatched PASS low-priority FIQ count = 0x00000015 21 high-priority FIQ count = 0x00000014 20 nested FIQ count = 0x00000014 20 of 20 nested max FIQ depth = 0x00000002 FIQ depth now = 0x00000000 F2 FIQ nested inside an FIQ handler PASS F3 FIQ nesting unwound to depth zero PASS F4 IRQ tick undisturbed by FIQ work PASS F5 lower-priority thread still scheduled PASS F6 no unexpected Group 0 INTID PASS No regression, both configurations checked on the board. In the FIQ build the ThreadX demo still reports 100 ticks with 20 preemptions and the boot image still passes its cache and protection checks. In the default build the demo is unchanged and the image links no FIQ or Group 0 symbol at all, so the work is absent rather than dormant where it is not wanted -- worth confirming on hardware rather than reasoning about, because the default build now reaches the FIQ vector through a new label even though that label only branches to the fault reporter. entry.S assembles in all four combinations of TX_R52_USE_THREADX_IRQ and FIQ support, on both toolchains, and every file builds with GNU without warnings and with Arm Toolchain for Embedded 22.1.0. Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>