serial hang in qemu-system-ppc64 -M pseries

Rob Landley rob at landley.net
Thu Apr 28 16:04:35 AEST 2022



On 4/28/22 00:41, Rob Landley wrote:
> On 4/27/22 10:27, Thomas Huth wrote:
>> On 26/04/2022 12.26, Rob Landley wrote:
>>> When I cut and paste 80-ish characters of text into the Linux serial console, it
>>> reads 16 characters and stops. When I hit space, it reads another 16 characters,
>>> and if I keep at it will eventually catch up without losing data. If I type,
>>> every character shows up immediately.
>> 
>> That "16" certainly comes from VTERM_BUFSIZE in hw/char/spapr_vty.c in the 
>> QEMU sources, I think.
>> 
>>> (On other qemu targets and kernels I can cut and paste an entire uuencoded
>>> binary and it goes through just fine in one go, but this target hangs with big
>>> pastes until I hit keys.)
>>> 
>>> Is this a qemu-side bug, or a kernel-side bug?
>>> 
>>> Kernel config attached (linux 5.18-rc3 or thereabouts), qemu invocation is:
>>> 
>>> qemu-system-ppc64 -M pseries -vga none -nographic -no-reboot -m 256 -kernel
>>> vmlinux -initrd powerpc64leroot.cpio.gz -append "panic=1 HOST=powerpc64le
>>> console=hvc0"
>> 
>> Which version of QEMU are you using?
> 
> $ qemu-system-ppc64 --version
> QEMU emulator version 6.2.92 (v6.2.0-rc2)
> Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers

Just confirmed it behaves the same with current git (commit cf6f26d6f9b2).

Rob


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