Re: [Qemu-devel] [PATCH v3 03/10] raven: move BIOS loading from board code to PCI host

["Hervé Poussineau" <hpoussin@reactos.org>]

Hi,

Andreas Färber a écrit :
> Hi,
> 
> Am 05.11.2013 00:09, schrieb Hervé Poussineau:
>> Raven datasheet explains where firmware lives in system memory, so do
>> it there instead of in board code. Other boards using the same PCI
>> host will not have to copy the firmware loading code.
> 
> This part we had discussed and no one objected to the approach, so OK.
> 
>> However, add a specific hack for Open Hack'Ware, which provides only
>> a 512KB blob to be loaded at 0xfff00000, but expects valid code at
>> 0xfffffffc (specific Open Hack'Ware reset instruction pointer).
> 
> Was this part explained before? I don't spot the equivalent in the
> deleted code. If this is a new workaround, I would rather like to put it
> in a separate patch for bisecting (can offer to do that myself then).
> What are the symptoms? I am testing all these patches with OHW.

Old code does (error checking removed):
 >> -            bios_size = get_image_size(filename);
 >> -                bios_addr = (uint32_t)(-bios_size);
 >> -                bios_size = load_image_targphys(filename, bios_addr,
Ie, bios_addr = -512KB (size of OHW blob) = 0xfff80000
and firmware is loaded in the range 0xfff80000-0xffffffff
OHW expects reset instruction pointer to be 0xfffffffc (not valid for 
604, but that's not the point now), which contains a valid instruction.
Note that range 0xfff00000-0xfff7ffff is empty.

Datasheet for raven says that firmware is at 0xfff00000, so I changed 
code to:
+#define BIOS_SIZE (1024 * 1024)
+                  bios_addr = (uint32_t)(-BIOS_SIZE);
+                  bios_size = load_image_targphys(filename, bios_addr,
+                                                  bios_size);
Ie, bios_addr = -1MB = 0xfff00000
and firmware is loaded in the range 0xfff00000-0xfff7ffff.
This doesn't work due to reset instruction pointer which now is pointing 
to empty memory, and symptoms are an empty screen on OHW.

So, I'm adding this hack for OHW, to mirror the 0xfff00000-0xfff7ffff 
range to 0xfff80000-0xffffffff.

So, this patch is a small functional change, as it adds a copy of the 
firmware in a new range 0xfff00000-0xfff7ffff, but I think we can live 
with it.

We'll be able to remove it once we switch to another firmware which uses 
the right reset instruction pointer.

Regards,

Hervé

>> Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
>> ---
>>  hw/pci-host/prep.c |   51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  hw/ppc/prep.c      |   50 +++++++++++++-------------------------------------
>>  2 files changed, 64 insertions(+), 37 deletions(-)
> [...]
>> diff --git a/hw/ppc/prep.c b/hw/ppc/prep.c
>> index 9f8538c..8a09e2b 100644
>> --- a/hw/ppc/prep.c
>> +++ b/hw/ppc/prep.c
> [...]
>> @@ -510,41 +509,13 @@ static void ppc_prep_init(QEMUMachineInitArgs *args)
>>      memory_region_add_subregion(sysmem, 0, ram);
>>  
>>      /* allocate and load BIOS */
>> -    memory_region_init_ram(bios, NULL, "ppc_prep.bios", BIOS_SIZE);
>> -    memory_region_set_readonly(bios, true);
>> -    memory_region_add_subregion(sysmem, (uint32_t)(-BIOS_SIZE), bios);
>> -    vmstate_register_ram_global(bios);
>> -    if (bios_name == NULL)
>> -        bios_name = BIOS_FILENAME;
>> -    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
>> -    if (filename) {
>> -        bios_size = load_elf(filename, NULL, NULL, NULL,
>> -                             NULL, NULL, 1, ELF_MACHINE, 0);
>> -        if (bios_size < 0) {
>> -            bios_size = get_image_size(filename);
>> -            if (bios_size > 0 && bios_size <= BIOS_SIZE) {
>> -                hwaddr bios_addr;
>> -                bios_size = (bios_size + 0xfff) & ~0xfff;
>> -                bios_addr = (uint32_t)(-bios_size);
>> -                bios_size = load_image_targphys(filename, bios_addr, bios_size);
>> -            }
>> -            if (bios_size > BIOS_SIZE) {
>> -                fprintf(stderr, "qemu: PReP bios '%s' is too large (0x%x)\n",
>> -                        bios_name, bios_size);
>> -                exit(1);
>> -            }
>> -        }
>> -    } else {
>> -        bios_size = -1;
>> -    }
>> -    if (bios_size < 0 && !qtest_enabled()) {
>> -        fprintf(stderr, "qemu: could not load PPC PReP bios '%s'\n",
>> -                bios_name);
>> -        exit(1);
>> -    }
>> -    if (filename) {
>> -        g_free(filename);
>> -    }
>> +    /* Open Hack'Ware hack: bios size is 512K and is loaded at 0xfff00000.
>> +     * However, reset address is 0xfffffffc. Mirror the bios from
>> +     * 0xfff00000 to 0xfff80000.
>> +     */
>> +    memory_region_init_alias(bios, NULL, "bios-alias", sysmem, 0xfff00000,
>> +                             0x00080000);
>> +    memory_region_add_subregion_overlap(sysmem, 0xfff80000, bios, 1);
>>  
>>      if (linux_boot) {
>>          kernel_base = KERNEL_LOAD_ADDR;
> [snip]
> 
>