Re: [PATCH v4] xen: arm: Update arm64 image header

[Julien Grall <julien.grall@arm.com>]

Hi Dirk,

On 27/06/2016 08:53, Dirk Behme wrote:
> +    if ( (end - start) > size ) {
> +        printk(XENLOG_ERR "Error: Kernel Image size: %lu bytes > bootmodule size: %lu bytes\n",
> +               zimage.image_size, (uint64_t)size);
> +        printk(XENLOG_ERR "The field 'size' does not match the size of blob!\n");
>          return -EINVAL;
> +    }

This patch is breaking boot on any ARM64 platform (UEFI and 
bootwrapper). The 'image_size' is the size of the kernel with BSS 
included. So the bootmodule will always be smaller than 'image_size'.

(XEN) Loading kernel from boot module @ 0000000080080000
(XEN) Error: Kernel Image size: 16482304 bytes > bootmodule size: 
15925760bytes
(XEN) The field 'size' does not match the size of blob!

So I think this field is intended to be used to tell the bootloader that 
kernel footprint will "image_size". So the bootloader will not attempt 
to place any modules (DT, ramdisk...) within this region.

We don't want to use this field to copy the kernel because we may end up 
to copy extra memory which could contain sensitive data.

Given that the main purpose of this patch is to use the field 
'image_size', I would just revert the patch until we figured out what to do.

Dirk, as this patch is meant to be ARM64 only, I am wondering how you 
were able to boot DOM0 with the patch applied.

Currently the pushgate for ARM64 is only build testing, so I should have 
tested this patch before giving my ack. I am sorry for that.

Regards,

-- 
Julien Grall

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