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Re: [Qemu-devel] [PATCH 12/19] hw/isa: Declare device little or big endi


From: Philippe Mathieu-Daudé
Subject: Re: [Qemu-devel] [PATCH 12/19] hw/isa: Declare device little or big endian
Date: Wed, 2 Oct 2019 13:31:00 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0

On 8/26/19 4:21 PM, Tony Nguyen wrote:
For each device declared with DEVICE_NATIVE_ENDIAN, find the set of
targets from the set of target/hw/*/device.o.

If the set of targets are all little or all big endian, re-declare
as DEVICE_LITTLE_ENDIAN or DEVICE_BIG_ENDIAN respectively.

Then, on inspection:
- if not used, re-declare as DEVICE_HOST_ENDIAN.
- if max/min size=1, re-declare as DEVICE_HOST_ENDIAN.

Here you say DEVICE_HOST_ENDIAN,

- if just a bit bucket, re-declare as DEVICE_HOST_ENDIAN
- if PCI, re-declare as DEVICE_LITTLE_ENDIAN.
- if for {ARM|unicore32} only, re-declare as DEVICE_LITTLE_ENDIAN.
- if for SPARC only, re-declare as DEVICE_BIG_ENDIAN.

Signed-off-by: Tony Nguyen <address@hidden>
---
  hw/isa/vt82c686.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
index 50bd28fa82..400f2b3c87 100644
--- a/hw/isa/vt82c686.c
+++ b/hw/isa/vt82c686.c
@@ -109,7 +109,7 @@ static uint64_t superio_ioport_readb(void *opaque, hwaddr 
addr, unsigned size)
  static const MemoryRegionOps superio_ops = {
      .read = superio_ioport_readb,
      .write = superio_ioport_writeb,
-    .endianness = DEVICE_NATIVE_ENDIAN,
+    .endianness = DEVICE_LITTLE_ENDIAN,

But here you use DEVICE_LITTLE_ENDIAN.

For 8-bit I/O port endianess doesn't matter, so I'm not sure what is the correct choice. Can we simply remove the .endianness line, since the won't be ever used?

      .impl = {
          .min_access_size = 1,
          .max_access_size = 1,





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