Hi Stefano, On 14 February 2017 at 03:14, Stefano Stabellini <sstabell...@kernel.org> wrote: > On Mon, 13 Feb 2017, Bhupinder Thakur wrote: >> Hi Stefano, >> >> On 9 February 2017 at 05:40, Stefano Stabellini <sstabell...@kernel.org> >> wrote: >> > On Wed, 8 Feb 2017, Bhupinder Thakur wrote: >> >> Hi Julien, >> >> >> >> On 3 February 2017 at 19:38, Julien Grall <julien.gr...@arm.com> wrote: >> >> > So if I understand correctly, you don't receive anymore output. Correct? >> >> > Have you tried to see whether the pl011 driver is receiving interrupt or >> >> > even Linux calling it. >> >> >> >> The pl011 driver is not receiving the interrupts (I put a >> >> HYPERVISOR_console_io() call inside the interrupt handler and I do not >> >> see the print on the xen console) . When the console is in this state, >> >> if I keep typing the characters on the console then Xen keeps raising >> >> the interrupts (for each character typed) but all those interrupts are >> >> marked as inflight. So it seems that interrupt is not getting cleared >> >> in GIC. Which GIC function can I look at to further debug what is the >> >> issue? >> >> >> >> Earlier, when I used to manually write characters to /dev/ttyAMA0 then >> >> I used to receive the interrupts all fine. >> > >> > DomU doesn't get emulated PL011 interrupts from Xen? Make sure you don't >> > mark the interrupt as a real hardware interrupt by mistake >> > (GICH_V2_LR_HW). At the same time, check that the virtual PL011 >> > interrupt has been added correctly to the LRs >> > (xen/arch/arm/gic-v2.c:gicv2_update_lr). >> >> I verified that the PL011 interrupt is getting marked pending by Xen >> but guest does not receive it. I am not sure if the local interrupt >> delivery is disabled on the guest because of which it may not be >> receiving the interrupts. Is there a way to verify that interrupts are >> indeed disabled at that point. Since the interrupt delivery works fine >> when I manually read/write characters to /dev/ttyAMA0, I think there >> is no issue from the Xen side in terms of raising an interrupt. >> >> One observation is that pl011_request_port () calls request_mem_region >> () for the MMIO space allocated to pl011. The function returns -EBUSY >> indicating that the memory region is already in use. But when I do cat >> /proc/iomem, I do not see any overlaps. I am using 0x22000000 as the >> start of the pl011 MMIO space. I see the same error while booting the >> dom0 kernel also. >> >> I have attached the guest boot logs when console=ttyAMA0. I have added >> debug prints marked with [DEBUG]. I added debug prints in amba-pl011.c >> and serial_core.c. The output from the console seems to suddenly stop >> once the pl011 port is started. I have not added getty for ttyAMA0 in >> the /etc/inittab file. I believe auto-serial-console should be able to >> attach a getty session to ttyAMA0 automatically (i did try with adding >> a getty command in the inittab file but that did not solve the issue). >> >> Towards the end of the log, we can see that every time a character is >> typed, Xen raises an interrupt and the characters keep getting >> collected in the IN RING buffer (in_prod keeps incrementing). Later >> interrupts remain in inflight as the earlier interrupt is not cleared. > > Let me get this straight: who is printing all those messages we see on > the guest console (xl console guest) up until "Freeing unused kernel > memory"? Is it the early pl011 driver? Or is it the Xen PV console > driver? > > Are you using a DEBUG build of Xen? Only DEBUG builds allow DomUs to > issue HYPERVISOR_console_io hypercalls. You might want to check that > do_console_io in Xen is letting DomU calls through. > > Otherwise pl011_int might actually be called but the printk might not > show up on the Xen console. > > The interrupt is enabled from Xen point of view, otherwise it would not > be added to the LR. However Linux might still refuse to call the > interrupt handler for some reason. You might want to add a printk in the > Linux generic interrupt handler, probably > kernel/irq/chip.c:handle_fasteoi_irq in your case.
The pl011 console is working now. I did not fix any thing specific except I cleaned up the debug code which I had added. I am not sure if some of my debug code was causing the issue. After cleaning up the debug code and building the code afresh, I started receiving the interrupts and input/output on the console is working fine. Now I am able to execute commands on the console. Regards, Bhupinder _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
