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* Re: [PATCH for-6.2 12/43] target/sh4: Implement do_unaligned_access for user-only
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@ 2021-07-30  0:01     ` Richard Henderson
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From: Richard Henderson @ 2021-07-30  0:01 UTC (permalink / raw)
  To: Peter Maydell; +Cc: QEMU Developers, Yoshinori Sato, Linux-sh list

On 7/29/21 3:52 AM, Peter Maydell wrote:
> sh4 kernel default for unaligned accesses seems to be "warn and fixup",
> not SIGBUS, unless the user changes that by writing to /proc/cpu/alignment
> or the process changes it via prctl().

We will still need this for load-locked/store-conditional (MOVLI/MOVCO).

It appears that the sh4 kernel fails to decode these properly, and will do something ugly, 
like interpreting MOVLI as a multiple-store instead of a load.

There are also other instructions that the kernel does not attempt to handle, such as MAC. 
  I suppose we could begin with turning off TARGET_ALIGNED_ONLY for sh4-linux-user, then 
re-enabling MO_ALIGN for the atomics (at least).


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2021-07-30  0:01     ` [PATCH for-6.2 12/43] target/sh4: Implement do_unaligned_access for user-only Richard Henderson

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