Messages in this thread | | | Subject | Re: [ANNOUNCE] v5.0.3-rt1 | From | Julien Grall <> | Date | Tue, 26 Mar 2019 10:26:31 +0000 |
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Hi John,
On 3/25/19 10:34 AM, John Ogness wrote: > On 2019-03-25, Julien Grall <julien.grall@arm.com> wrote: >> [...] >> [ 1.169151] 002: Serial: AMBA PL011 UART driver >> [ 1.254891] 002: 7ff80000.uart: ttyAMA0 at MMIO 0x7ff80000 (irq = 32, base_baud = 0) is a PL011 rev3 >> [ 1.255007] 002: printk: console [ttyAMA0] enabled > > The ttyAMA drivers do not have support for atomic printing, so it is not > the new atomic feature that is causing the mangling. For your setup, all > printk console printing is being handled within a specific context, the > printk kernel thread.
This series is somehow making worst when using ttyAMA0. I haven't see any mangling with 4.19-rt.
> > It looks to me like some userspace application (systemd?) is writing > directly to /dev/ttyAMA0. If the kernel is also writing to this device > (because it is setup as a console), then the output will be > mangled. There is no high-level synchronization between console output > and directly writing to UART devices. Maybe you need to set your > loglevel so that the kernel does not do the printing? For example, > loglevel=1?
I am a bit confused with your suggestion. This would basically means I would not be able to see kernel warning. So this would impair any development on Linux-rt.
> > You should see this problem with older kernel versions as well.
I have tried with 4.19-rt and didn't see a similar issue. The trace comes pretty clean in one go. With 5.0-rt, the trace never come clean.
Cheers,
-- Julien Grall
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