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Re: [Qemu-arm] [PATCH v2] Support u-boot noload images for arm as used b

From: Nick Hudson
Subject: Re: [Qemu-arm] [PATCH v2] Support u-boot noload images for arm as used by, NetBSD/evbarm GENERIC kernel.
Date: Sat, 1 Dec 2018 14:09:52 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 30/11/2018 17:18, Peter Maydell wrote:
On Thu, 29 Nov 2018 at 20:22, Nick Hudson <address@hidden> wrote:
noload kernels are loaded with the u-boot image header and as a result
the header size needs adding to the entry point.  Fake up a hdr so the
kernel image is loaded at the right address and the entry point is
adjusted appropriately.

The bootloader fits in the space that the uboot header would have occupied.

Update the load_uimage API to allow passing of load address when an image
doesn't specify one.

Signed-off-by: Nick Hudson <address@hidden>
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 67a0af84ac..10ff0ff76d 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -163,7 +163,8 @@ int load_aout(const char *filename, hwaddr addr, int max_sz,
  /** load_uimage_as:
   * @filename: Path of uimage file
   * @ep: Populated with program entry point. Ignored if NULL.
- * @loadaddr: Populated with the load address. Ignored if NULL.
+ * @loadaddr: load address if none specified in the image. Populated with the
+ *            load address. Ignored if NULL.
This API change will break some existing users. For instance
hw/microblaze/boot.c does this:
             hwaddr uentry, loadaddr;

             kernel_size = load_uimage(kernel_filename, &uentry, &loadaddr, 0,
                                       NULL, NULL);

I did a bit more digging and the same (ab)use of loadaddr to pass

a value is used by load_ramdisk{,_as}.  Hopefully, I can do the same

for kernel_noload?

which is a legitimate use of the current API, but your changes will
mean that load_uboot_image() will be using an uninitialized
variable. Getting every call site that cares about the returned
result from loadaddr to also provide a valid default load
address as input is going to be really painful, so I think we
need to figure out an API for this function that doesn't
make the input (default load address) argument the same
parameter as the output (where we actually loaded the image)

I have version 3 ready with fixing these callers.

We should also make the load_uboot_image() function print an
error message if we don't load the file because it needs a
default load address and the caller didn't pass one
("this image format cannot be loaded on this machine type",
or similar).
Fixed in version 3.

PS: our coding style wants {} on all if()s -- scripts/checkpatch.pl
can help catch this kind of nit.

There are lots of errors from this without my changes :(

-- PMM



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