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Date: Thu, 17 Oct 2013 13:31:38 +0100
From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
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Subject: Re: [Qemu-devel] [PATCH 1/2] sun4m: Add Sun CG3 framebuffer and
 corresponding OpenBIOS FCode ROM
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Blue Swirl <blauwirbel@gmail.com>, Bob Breuer <breuerr@mc.net>, QEMU Developers <qemu-devel@nongnu.org>, Artyom Tarasenko <atar4qemu@gmail.com>

On 15/10/13 22:46, Peter Maydell wrote:

> On 15 October 2013 21:19, Mark Cave-Ayland
> <mark.cave-ayland@ilande.co.uk>  wrote:
>> +    /* FCode ROM */
>> +    memory_region_init_ram(&s->rom, NULL, "cg3.prom", FCODE_MAX_ROM_SIZE);
>> +    vmstate_register_ram_global(&s->rom);
>> +    memory_region_set_readonly(&s->rom, true);
>> +    sysbus_init_mmio(dev,&s->rom);
>> +
>> +    fcode_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, CG3_ROM_FILE);
>> +    if (fcode_filename) {
>> +        ret = load_image_targphys(fcode_filename, s->prom_addr,
>> +                                  FCODE_MAX_ROM_SIZE);
>> +    }
>
> Ideally we would have a 'load image into RAM memory region' function,
> and then we wouldn't need to pass the device the address of its own
> memory region. Oh well...

Yes, definitely the ROM image code is lacking from post-MemoryRegion 
love. For example load_image_targphys() indirectly creates a 
MemoryRegion to hold the loaded ROM contents, but it only becomes 
visible (presumably because of SysBus) when another RAM MemoryRegion is 
installed at the same address. Hence you actually end up having to claim 
twice the memory requirement of your original ROM.


ATB,

Mark.