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Re: [PATCH v3] hw/scsi/lsi53c895a: add timer to scripts processing


From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v3] hw/scsi/lsi53c895a: add timer to scripts processing
Date: Fri, 8 Mar 2024 09:14:39 +0100
User-agent: Mozilla Thunderbird

On 4/3/24 17:37, Sven Schnelle wrote:
HP-UX 10.20 seems to make the lsi53c895a spinning on a memory location
under certain circumstances. As the SCSI controller and CPU are not
running at the same time this loop will never finish. After some
time, the check loop interrupts with a unexpected device disconnect.
This works, but is slow because the kernel resets the scsi controller.
Instead of signaling UDC, start a timer and exit the loop. Until the
timer fires, the CPU can process instructions which might change the
memory location.

The limit of instructions is also reduced because scripts running on
the SCSI processor are usually very short. This keeps the time until
the loop is exited short.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
---
  hw/scsi/lsi53c895a.c | 43 +++++++++++++++++++++++++++++++++----------
  hw/scsi/trace-events |  2 ++
  2 files changed, 35 insertions(+), 10 deletions(-)

I suppose Paolo is going to take this patch, otherwise I can
queue it via hw-misc tree.



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