[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Bug 1850378] Re: RISC-V unreliable IPIs
From: |
Launchpad Bug Tracker |
Subject: |
[Bug 1850378] Re: RISC-V unreliable IPIs |
Date: |
Tue, 22 Jun 2021 04:18:38 -0000 |
[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1850378
Title:
RISC-V unreliable IPIs
Status in QEMU:
Expired
Bug description:
I am working on a project with custom inter processor interrupts (IPIs) on
the RISC-V virt machine.
After upgrading from version 3.1.0 to 4.1.0 which fixes a related issue
(https://github.com/riscv/riscv-qemu/issues/132) I am able to use the CPU
hotplug feature.
However, if I try to use IPIs for communication between two cores, the
wfi instruction behaves strangely. Either it does not return, or it
returns on timer interrupts, even though they are disabled. The code,
I use on one core to wait for an interrupt is the following.
csr_clear(sie, SIE_SEIE | SIE_STIE);
do {
wait_for_interrupt();
sipval = csr_read(sip);
sieval = csr_read(sie);
scauseval = csr_read(scause) & 0xFF;
/* only break if wfi returns for an software interrupt */
} while ((sipval & sieval) == 0 && scauseval != 1);
csr_set(sie, SIE_SEIE | SIE_STIE);
Since the resulting sequence does not seem to be deterministic, my
guess is, that it has something to do with the communication of qemu's
threads for the different cores.
Update:
The exact same setup works fine in spike (the actual sim, not the qemu
board), which might give a hint, that it is related to the interrupt controller
implementation.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1850378/+subscriptions
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Bug 1850378] Re: RISC-V unreliable IPIs,
Launchpad Bug Tracker <=