Re: [PATCH v2 8/8] xen: arm: allocate more than one bank for 1:1 domain 0 if needed

[Julien Grall <julien.grall@linaro.org>]

Hi Ian,

On 11/06/14 17:40, Ian Campbell wrote:
> +        bank->start = start;
> +        bank->size = size;
> +        kinfo->mem.nr_banks++;
> +        return true;
> +    }
> +
> +    panic("Failed add pages to DOM0 memory bank");

This can happen when there is no more bank, right? How likely will Xen 
fill the 8 banks?

Shall we just continue with only the current number of bank?

> +}
> +
> +/*
> + * This is all pretty horrible.
> + *
> + * Requirements:
> + *
> + * 1. The dom0 kernel should be loaded within the first 128MB of RAM. This
> + *    is necessary at least for Linux zImage kernels, which are all we
> + *    support today.
> + * 2. We want to put the dom0 kernel, ramdisk and DTB in the same
> + *    bank. Partly this is just easier for us to deal with, but also
> + *    the ramdisk and DTB must be placed within a certain proximity of
> + *    the kernel within RAM.
> + * 3. For 32-bit dom0 we want to place as much of the RAM as we
> + *    reasonably can below 4GB, so that it can be used by non-LPAE
> + *    enabled kernels.
> + * 4. For 32-bit dom0 the kernel must be located below 4GB.
> + * 5. We want to have a few largers banks rather than many smaller ones.
> + *
> + * For the first two requirements we need to make sure that the lowest
> + * bank is sufficiently large.
> + *
> + * For convenience we also sort the banks by physical address.

IIRC, some kernel version (< 3.15) is assuming that the memory bank are 
ordered.

Regards,

-- 
Julien Grall