[Qemu-devel] [PATCH] hw/arm/boot: Increase compliance with kernel arm64 boot protocol.

[Stewart Hildebrand <Stewart.Hildebrand@dornerworks.com>]

"The Image must be placed text_offset bytes from a 2MB aligned base
address anywhere in usable system RAM and called there."

For the virt board, we write our startup bootloader at the very
bottom of RAM, so that bit can't be used for the image. To avoid
overlap in case the image requests to be loaded at an offset
smaller than our bootloader, we increment the load offset to the
next 2MB.

This fixes a boot failure for Xen AArch64.

Signed-off-by: Stewart Hildebrand <stewart.hildebrand@dornerworks.com>
---
 hw/arm/boot.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 20c71d7d96..559ddbcd53 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -919,6 +919,16 @@ static uint64_t load_aarch64_image(const char *filename, hwaddr mem_base,
         memcpy(&hdrvals, buffer + ARM64_TEXT_OFFSET_OFFSET, sizeof(hdrvals));
         if (hdrvals[1] != 0) {
             kernel_load_offset = le64_to_cpu(hdrvals[0]);
+
+            /* For the virt board, we write our startup "bootloader" at the very
+             * bottom of RAM, so that bit can't be used for the image. To avoid
+             * overlap in case the image requests to be loaded at an offset
+             * smaller than our bootloader, we increment the load offset to the
+             * next 2MB.
+             */
+            if (kernel_load_offset < FIXUP_MAX) {
+                kernel_load_offset += 2 << 20;
+            }
         }
     }
 
-- 
2.17.1