console: share the Uart by reference and add iprint - #5
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Signed-off-by: Graham MacDonald <grahamamacdonald@gmail.com>
Signed-off-by: Graham MacDonald <grahamamacdonald@gmail.com>
Signed-off-by: Graham MacDonald <grahamamacdonald@gmail.com>
req_buffer_va/req_buffer_pa held VirtRange/PhysRange values; name them req_buf_virtrange/req_buf_physrange like the rest of the file. Also drop an unused pub on mbox_virtrange.
Add port::irq with an RAII IrqGuard (mask IRQs on new, restore the previous state on drop; nestable; no-op until an arch registers its mask/restore hooks) and an interrupt-depth counter (enter_interrupt/ exit_interrupt/in_interrupt) so subsystems can either mask around locks shared with interrupt context or assert they are never used from it. aarch64 registers a DAIF-based implementation at early boot and brackets the trap handler with the depth counter. Other arches are unaffected: the guard is a no-op and in_interrupt is always false until they opt in.
The console Uart is now held as &'static dyn Uart rather than &mut: putb only needs a shared reference, and a shared reference lets the same Uart be aliased by the new direct-print path. Add iprint/iprintln in the tradition of Plan 9's iprint: mask IRQs, take only a best-effort bounded-spin interlock, and write polled bytes straight to the hardware, bypassing the console lock. This is the print for interrupt context, panic, and console/lock debugging; each arch registers a direct byte writer at console init. The console lock itself becomes thread-context-only, enforced with a debug assertion, so println no longer needs to mask IRQs around UART output. The aarch64 panic handler and trap handler switch to iprintln accordingly.
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The console Uart is now
&'static dyn Uartrather than&mut—putbonly needs a shared reference, and sharing lets the same Uart be aliased by the new direct-print path.Adds
iprint/iprintlnin the tradition of Plan 9's iprint: masks IRQs, takes only a best-effort bounded-spin interlock, and writes polled bytes straight to the hardware, bypassing the console lock. This is the print for interrupt context, panic, and console/lock debugging. The console lock becomes thread-context-only (debug-asserted), soprintlnno longer masks IRQs around UART output. The aarch64 panic and trap handlers switch toiprintln.Stacked on #4; review the last commit.