Re: [Qemu-devel] [RfC PATCH] vga: add mmio bar to standard vga

[Gerd Hoffmann <kraxel@redhat.com>]

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>> + *   0x0400 -> 0x041f  vga ioports (0x3c0 -> 0x3df), remapped 1:1
> 
> Do they support word accesses to set both index and data?
> 
>> + *   0x0500 -> 0x0515  bochs dispi interface registers, mapped flat without
>> + *                     index/data ports.  Use (index << 1) as offset for
>> + *                     (16bit) register access.
>> + */
> 
> BAR should disappear with -M old.

Sure.  I have a patch in flight which adds the pc-1.3 machine type, once
this is in I can easily add the compat stuff.

>> +static const MemoryRegionOps pci_vga_ioport_ops = {
>> +    .read = pci_vga_ioport_read,
>> +    .write = pci_vga_ioport_write,
>> +    .valid.min_access_size = 1,
>> +    .valid.max_access_size = 4,
>> +    .impl.min_access_size = 1,
>> +    .impl.max_access_size = 1,
>> +    .endianness = DEVICE_LITTLE_ENDIAN,
>> +};
> 
> Looks like word writes are supported provided the memory API breaks up
> writes in little endian order.  Better to make it explicit.

Like the attached incremental patch?

cheers,
  Gerd


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>From d46b14dfd74dcc37fe187dc76cd681ad7dbff2d5 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 19 Sep 2012 13:31:04 +0200
Subject: [PATCH] [fixup] vga mmio

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/vga-pci.c |   25 ++++++++++++++++++++++---
 1 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/hw/vga-pci.c b/hw/vga-pci.c
index e05e2ef..7fd305d 100644
--- a/hw/vga-pci.c
+++ b/hw/vga-pci.c
@@ -78,14 +78,33 @@ static uint64_t pci_vga_ioport_read(void *ptr, target_phys_addr_t addr,
                                     unsigned size)
 {
     PCIVGAState *d = ptr;
-    return vga_ioport_read(&d->vga, addr);
+    uint64_t ret = 0;
+
+    switch (size) {
+    case 1:
+        ret = vga_ioport_read(&d->vga, addr);
+        break;
+    case 2:
+        ret  = vga_ioport_read(&d->vga, addr);
+        ret |= vga_ioport_read(&d->vga, addr+1) << 8;
+        break;
+    }
+    return ret;
 }
 
 static void pci_vga_ioport_write(void *ptr, target_phys_addr_t addr,
                                  uint64_t val, unsigned size)
 {
     PCIVGAState *d = ptr;
-    vga_ioport_write(&d->vga, addr, val);
+    switch (size) {
+    case 1:
+        vga_ioport_write(&d->vga, addr, val);
+        break;
+    case 2:
+        vga_ioport_write(&d->vga, addr, val & 0xff);
+        vga_ioport_write(&d->vga, addr+1, (val >> 8) & 0xff);
+        break;
+    }
 }
 
 static const MemoryRegionOps pci_vga_ioport_ops = {
@@ -94,7 +113,7 @@ static const MemoryRegionOps pci_vga_ioport_ops = {
     .valid.min_access_size = 1,
     .valid.max_access_size = 4,
     .impl.min_access_size = 1,
-    .impl.max_access_size = 1,
+    .impl.max_access_size = 2,
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
-- 
1.7.1