Re: [PATCH 1/2] m68k/atari - stram: alloc ST-RAM pool even if kernel not in ST-RAM

[schmitz <schmitz@biophys.uni-duesseldorf.de>]

Geert,
>> Instead of mucking around with ioremap (which appears to
>> rely on the physical area being mappped by mem_init), use
>>     
>
> That's not true. E.g. I/O memory is never mapped by mem_init().
>   

Why, then, does the ioremap() of ST-RAM fail? Because the physical 
address is lower than the lowest currently mapped physical address?

>   
>> @@ -93,21 +92,54 @@ void __init atari_stram_init(void)
>>   */
>>  void __init atari_stram_reserve_pages(void *start_mem)
>>  {
>> -       /*
>> -        * always reserve first page of ST-RAM, the first 2 KiB are
>> -        * supervisor-only!
>> -        */
>> -       if (!kernel_in_stram)
>> -               reserve_bootmem(0, PAGE_SIZE, BOOTMEM_DEFAULT);
>> -
>> -       stram_pool.start = (resource_size_t)alloc_bootmem_low_pages(pool_size);
>> -       stram_pool.end = stram_pool.start + pool_size - 1;
>> -       request_resource(&iomem_resource, &stram_pool);
>> +       if (kernel_in_stram) {
>> +
>> +               stram_pool.start = (resource_size_t)alloc_bootmem_low_pages(pool_size);
>> +               stram_pool.end = stram_pool.start + pool_size - 1;
>> +               request_resource(&iomem_resource, &stram_pool);
>> +
>> +               printk("atari_stram pool: kernel in ST-RAM, using alloc_bootmem!\n");
>> +
>> +               printk("atari_stram pool: size = %lu bytes, resource = %pR\n",
>> +                        pool_size, &stram_pool);
>> +               printk("atari_stram pool: start = %p, end = %p\n",
>> +                         (void *) stram_pool.start, (void *) stram_pool.end);
>> +               printk("atari_stram pool: stram_virt_offset = %p\n",
>> +                         (void *) stram_virt_offset);
>> +       } else {
>> +               /*
>> +                * Skip page 0, as the fhe first 2 KiB are supervisor-only!
>> +                */
>> +
>> +               printk("atari_stram pool: kernel not in ST-RAM, using ioremap!\n");
>> +
>> +               stram_pool.start = PAGE_SIZE;
>> +               stram_pool.end = stram_pool.start + pool_size - 1;
>> +
>> +               request_resource(&iomem_resource, &stram_pool);
>> +
>> +               printk("atari_stram pool: size = %lu bytes, resource = %pR\n",
>> +                        pool_size, &stram_pool);
>> +               printk("atari_stram pool: start = %p, end = %p\n",
>> +                         (void *) stram_pool.start, (void *) stram_pool.end);
>> +
>> +               /* stram_virt_offset = ioremap(stram_pool.start, pool_size); */
>> +               stram_virt_offset = (unsigned long) 0xFF000000;
>> +
>> +               printk("atari_stram pool: stram_virt_offset = %p\n",
>> +                         (void *) stram_virt_offset);
>> +       }
>>     
>
> If you reorder some lines, you can share more code between the "if" and
> "else" cases.
>
>   
>> +void *atari_stram_to_virt(unsigned long phys)
>> +{
>> +       return (void *)(phys + stram_virt_offset);
>>  }
>>
>> +void *atari_stram_to_phys(unsigned long virt)
>>     
>
> This should be "unsigned long atari_stram_to_phys(void *)",
> allowing to remove a few casts in the callers...
>   

Yep, that was a bit awkward to cast. This clearly needs a few more 
iterations.

Thanks for your feedback!

Cheers,

    Michael