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