[Qemu-devel] [Bug 1815721] [NEW] RISC-V PLIC enable interrupt for multicore

[RTOS Pharos]

Public bug reported:

Hello all,

There is a bug in Qemu related to the enabling of external interrupts
for multicores (Virt machine).

After correcting Qemu as described in #1815078
(https://bugs.launchpad.net/qemu/+bug/1815078), when we try to enable
interrupts for core 1 at address 0x0C00_2080 we don't seem to be able to
trigger an external interrupt  (e.g. UART0).

This works perfectly for core 0, but fore core 1 it does not work at
all. I assume that given bug #1815078 does not enable any external
interrupt then this feature has not been tested. I tried to look at the
qemu source code but with no luck so far.

I guess the problem is related to function parse_hart_config (in
sfive_plic.c) that initializes incorrectly the
plic->addr_config[addrid].hartid, which is later on read in
sifive_plic_update. But this is a guess.

Best regards,
Pharos team

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1815721

Title:
  RISC-V PLIC enable interrupt for multicore

Status in QEMU:
  New

Bug description:
  Hello all,

  There is a bug in Qemu related to the enabling of external interrupts
  for multicores (Virt machine).

  After correcting Qemu as described in #1815078
  (https://bugs.launchpad.net/qemu/+bug/1815078), when we try to enable
  interrupts for core 1 at address 0x0C00_2080 we don't seem to be able
  to trigger an external interrupt  (e.g. UART0).

  This works perfectly for core 0, but fore core 1 it does not work at
  all. I assume that given bug #1815078 does not enable any external
  interrupt then this feature has not been tested. I tried to look at
  the qemu source code but with no luck so far.

  I guess the problem is related to function parse_hart_config (in
  sfive_plic.c) that initializes incorrectly the
  plic->addr_config[addrid].hartid, which is later on read in
  sifive_plic_update. But this is a guess.

  Best regards,
  Pharos team

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