Re: [Qemu-devel] [PATCH 2/2] vga: Fix portio list conversion fallouts

[Avi Kivity <avi@redhat.com>]

On 09/18/2011 07:28 PM, Jan Kiszka wrote:
> On 2011-09-18 17:51, Avi Kivity wrote:
> >  On 09/18/2011 03:44 PM, Jan Kiszka wrote:
> >>  From: Jan Kiszka<jan.kiszka@siemens.com>
> >>
> >>  Fix copy&paste errors and reduce duplications of the BOCHS VBE ranges.
> >>
> >>  Signed-off-by: Jan Kiszka<jan.kiszka@siemens.com>
> >>  ---
> >>
> >>    #ifdef CONFIG_BOCHS_VBE
> >>    static const MemoryRegionPortio vbe_portio_list[] = {
> >>  -# ifdef TARGET_I386
> >>        { 0, 1, 2, .read = vbe_ioport_read_index, .write =
> >>  vbe_ioport_write_index },
> >>  +# ifdef TARGET_I386
> >
> >  Strange how the card knows what target it's plugged into.  Fixing this
> >  is going to involve major pain - need to update the bios and need to
> >  provide backwards compatibility.  All this assuming guests don't
> >  hardcode the address.
> >
> >  Anyway I find the deduplication makes the code harder to read.
>
> That line is rather tricky to deduplicate in mind. So it's not nice for
> our readers keeping it duplicated around.

I don't think it should be deduplicated.  The device is providing two 
separate ABIs.

> >
> >>        { 1, 1, 2, .read = vbe_ioport_read_data, .write =
> >>  vbe_ioport_write_data },
> >>    # else
> >>  -    { 0, 2, 2, .read = vbe_ioport_read_index, .write =
> >>  vbe_ioport_write_index },
> >>  -    { 2, 2, 2, .read = vbe_ioport_read_data, .write =
> >>  vbe_ioport_write_data },
> >>  +    { 2, 1, 2, .read = vbe_ioport_read_data, .write =
> >>  vbe_ioport_write_data },
> >
> >  Is this correct?  length 1 region with size 2?
>
> Yes, it prevents accesses on base+1.
>

Why disallow it?

For the general case or a 2-byte access near the end of a region, we 
need to provide a general fix.

-- 
error compiling committee.c: too many arguments to function