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Date: Thu, 28 May 2015 16:42:17 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] i386: drop FDC in pc-q35-2.4+ if neither
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To: Gerd Hoffmann <kraxel@redhat.com>, "Gabriel L. Somlo" <gsomlo@gmail.com>
Cc: John Snow <jsnow@redhat.com>, mst@redhat.com, lersek@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com



On 28/05/2015 15:52, Gerd Hoffmann wrote:
> @@ -494,7 +494,7 @@ static void ich9_lpc_machine_ready(Notifier *n, void *opaque)
>          /* lpt */
>          pci_conf[0x82] |= 0x04;
>      }
> -    if (memory_region_present(io_as, 0x3f0)) {
> +    if (memory_region_present(io_as, 0x3f2)) {
>          /* floppy */
>          pci_conf[0x82] |= 0x08;
>      }
> 
> Oh, and this ...
> 
> $ virsh qemu-monitor-command fedora-org-q35.base --hmp "info mtree" | grep fdc
>     00000000000003f1-00000000000003f5 (prio 0, RW): fdc
>     00000000000003f7-00000000000003f7 (prio 0, RW): fdc
> 
> ... looks fishy too.  Shouldn't that be 0x3f2-0x3f6 for the first range?

I think 0x3f0-0x3f5 based on this:

hw/block/fdc.c:    FD_REG_SRA = 0x00,
hw/block/fdc.c:    FD_REG_SRB = 0x01,
hw/block/fdc.c:    FD_REG_DOR = 0x02,
hw/block/fdc.c:    FD_REG_TDR = 0x03,
hw/block/fdc.c:    FD_REG_MSR = 0x04,
hw/block/fdc.c:    FD_REG_DSR = 0x04,
hw/block/fdc.c:    FD_REG_FIFO = 0x05,
hw/block/fdc.c:    FD_REG_DIR = 0x07,
hw/block/fdc.c:    FD_REG_CCR = 0x07,

So:

diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index d8a8edd..c761291 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -2186,7 +2186,7 @@ static void fdctrl_realize_common(FDCtrl *fdctrl, Error **errp)
 }
 
 static const MemoryRegionPortio fdc_portio_list[] = {
-    { 1, 5, 1, .read = fdctrl_read, .write = fdctrl_write },
+    { 0, 6, 1, .read = fdctrl_read, .write = fdctrl_write },
     { 7, 1, 1, .read = fdctrl_read, .write = fdctrl_write },
     PORTIO_END_OF_LIST(),
 };

Paolo