Re: [PATCH v3 11/20] nubus-device: add romfile property for loading declaration ROMs

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

On 16/09/2021 14:06, Markus Armbruster wrote:

> Philippe Mathieu-Daudé <f4bug@amsat.org> writes:
> 
>> On 9/16/21 12:05 PM, Mark Cave-Ayland wrote:
>>> The declaration ROM is located at the top-most address of the standard slot
>>> space.
>>>
>>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>> ---
>>>   hw/nubus/nubus-device.c  | 43 +++++++++++++++++++++++++++++++++++++++-
>>>   include/hw/nubus/nubus.h |  6 ++++++
>>>   2 files changed, 48 insertions(+), 1 deletion(-)
>>
>>> @@ -38,10 +43,46 @@ static void nubus_device_realize(DeviceState *dev, Error **errp)
>>>       memory_region_add_subregion(&nubus->slot_io, slot_offset,
>>>                                   &nd->slot_mem);
>>>       g_free(name);
>>> +
>>> +    /* Declaration ROM */
>>> +    if (nd->romfile != NULL) {
>>> +        path = qemu_find_file(QEMU_FILE_TYPE_BIOS, nd->romfile);
>>> +        if (path == NULL) {
>>> +            path = g_strdup(nd->romfile);
>>> +        }
>>> +
>>> +        size = get_image_size(path);
>>> +        if (size < 0) {
>>> +            error_setg(errp, "failed to find romfile \"%s\"", nd->romfile);
>>> +            g_free(path);
>>> +            return;
>>> +        } else if (size == 0) {
>>> +            error_setg(errp, "romfile \"%s\" is empty", nd->romfile);
>>> +            g_free(path);
>>> +            return;
>>> +        } else if (size > NUBUS_DECL_ROM_MAX_SIZE) {
>>> +            error_setg(errp, "romfile \"%s\" too large (maximum size 128K)",
>>> +                       nd->romfile);
>>> +            g_free(path);
>>> +            return;
>>> +        }
>>> +
>>> +        name = g_strdup_printf("nubus-slot-%x-declaration-rom", nd->slot);
>>> +        memory_region_init_rom(&nd->decl_rom, OBJECT(dev), name, size,
>>> +                               &error_fatal);
> 
> Is this error expected to happen?
> 
> If yes, you should quite probably propagate it.
> 
> If no, &error_abort.

(goes and looks)

Ultimately this gets set from memory_region_init_rom_device_nomigrate() where err is 
returned from qemu_ram_alloc() which is fairly fatal. So I guess this should be 
&error_abort then?

Note that I copied that part of the logic from hw/pci/pci.c's pci_add_option_rom() so 
it may also need to be adjusted there.

>>> +        ret = load_image_mr(path, &nd->decl_rom);
>>
>> load_image_mr() already calls get_image_size(), rom_add_file() and
>> qemu_find_file(). *But* it doesn't takes and Error handle, and report
>> error using fprintf()...
> 
> ... except when they don't:
> 
>      int load_image_mr(const char *filename, MemoryRegion *mr)
>      {
>          int size;
> 
>          if (!memory_access_is_direct(mr, false)) {
>              /* Can only load an image into RAM or ROM */
> --->        return -1;
>          }
> 
>          size = get_image_size(filename);
> 
>          if (size < 0 || size > memory_region_size(mr)) {
>              return -1;
>          }
>          if (size > 0) {
>              if (rom_add_file_mr(filename, mr, -1) < 0) {
>                  return -1;
>              }
>          }
>          return size;
>      }
> 
> Hot mess!
> 
>>                           So unfortunately rom_add*() functions are
>> kinda outdated and you are doing the right thing to propagate detailled
>> errors.
> 
> I can't see errors being propagated, only a warn_report()...
> 
>>          Therefore:
>>
>> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>
>>> +        g_free(path);
>>> +        if (ret < 0) {
>>> +            warn_report("nubus-device: could not load prom '%s'", nd->romfile);
> 
> ... here.

Looking again at pci_add_option_rom() then perhaps this should be error_setg() 
instead: if you are explicitly trying to load a ROM image, then you should at least 
be able to get the filename correct.

>>> +        }
>>> +        memory_region_add_subregion(&nd->slot_mem, NUBUS_SLOT_SIZE - size,
>>> +                                    &nd->decl_rom);
>>> +    }
>>>   }


ATB,

Mark.