Re: [PATCH 0/6] hw/arm: Fix smpboot[] on big-endian hosts and remove tswap32()

[Philippe Mathieu-Daudé]

On 22/12/22 22:55, Philippe Mathieu-Daudé wrote:
> ARM CPUs fetch instructions in little-endian.
>
> smpboot[] encoded instructions are written in little-endian.
>
> We call tswap32() on the array. tswap32 function swap a 32-bit
> value if the target endianness doesn't match the host one.
> Otherwise it is a NOP.
>
> * On a little-endian host, the array is stored as it. tswap32()
>    is a NOP, and the vCPU fetches the instructions as it, in
>    little-endian.
>
> * On a big-endian host, the array is stored as it. tswap32()
>    swap the instructions to little-endian, and the vCPU fetches
>    the instructions as it, in little-endian.
>
> Using tswap() on system emulation is a bit odd: while the target
> particularities might change the system emulation, the host ones
> (such its endianness) shouldn't interfere.
>
> We can simplify by using const_le32() to always store the
> instructions in the array in little-endian, removing the need
> for the dubious tswap().
>
> Two boards which weren't swapping (aspeed and raspi) are fixed.
>
> Tested running ARM avocado tests on x86_64 and s390x.
>
> Philippe Mathieu-Daudé (6):
>    hw/arm/aspeed: Fix smpboot[] on big-endian hosts
>    hw/arm/raspi: Fix smpboot[] on big-endian hosts
>    hw/arm/exynos4210: Remove tswap32() calls and constify smpboot[]
>    hw/arm/npcm7xx: Remove tswap32() calls and constify smpboot[]
>    hw/arm/xilinx_zynq: Remove tswap32() calls and constify smpboot[]
>    hw/arm/boot: Remove tswap32() calls and constify board_setup_blob[]
>
>   hw/arm/aspeed.c      | 28 ++++++++++++------------
>   hw/arm/boot.c        | 52 +++++++++++++++++++-------------------------
>   hw/arm/exynos4210.c  | 48 ++++++++++++++++++----------------------
>   hw/arm/npcm7xx.c     | 49 +++++++++++++++++------------------------
>   hw/arm/raspi.c       | 46 +++++++++++++++++++--------------------
>   hw/arm/xilinx_zynq.c | 27 ++++++++++-------------
>   6 files changed, 112 insertions(+), 138 deletions(-)

I forgot to mention, checkpatch warns for 11 lines over 80chars, and
errors for 2 over 90chars. Since these are the assembler comments,
I choose to keep it that way for readability.