On 08/12/2022 13:51, Julien Grall wrote:
Hi,
Hi Julien,
Title extra NIT: I have seen it multiple time and so far refrain to
say it. Please use 'arm' rather than 'Arm'. This is for consistency in
the way we name the subsystem in the title.
I will take care of it henceforth.
On 08/12/2022 12:49, Ayan Kumar Halder wrote:
Currently, kernel_uimage_probe() does not set info->zimage.start. As a
result, it contains the default value (ie 0). This causes,
kernel_zimage_place() to treat the binary (contained within uImage) as
position independent executable. Thus, it loads it at an incorrect
address.
The correct approach would be to read "uimage.ep" and set
info->zimage.start. This will ensure that the binary is loaded at the
correct address.
In non-statically allocated setup, a user doesn't know where the
memory for dom0/domU will be allocated.
So I think this was correct to ignore the address. In fact, I am worry
that...
Signed-off-by: Ayan Kumar Halder <[email protected]>
---
I uncovered this issue while loading Zephyr as a dom0less domU with
Xen on
R52 FVP. Zephyr builds with static device tree. Thus, the load
address is
always fixed.
xen/arch/arm/kernel.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index 2556a45c38..e4e8c67669 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -222,6 +222,8 @@ static int __init kernel_uimage_probe(struct
kernel_info *info,
if ( len > size - sizeof(uimage) )
return -EINVAL;
+ info->zimage.start = be32_to_cpu(uimage.ep);
... this will now ended up to break anyone that may have set an
address but didn't care where it should be loaded.
Can we use a config option (STATIC_MEMORY or any option you may suggest)
to distinguish between the two ?
Or using some magic number (eg 0xdeadbeef) for uimage.ep which will
denote position independent ? This needs to be documented in
docs/misc/arm/booting.txt.
Or ...
I also understand your use case but now, we have contradictory
approaches. I am not entirely sure how we can solve it. We may have to
break those users (Cc some folks that may use it). But we should
figure out what is the alternative for them.
I am open to any alternative suggestion.
If we decide to break those users, then this should be documented in
the commit message and in docs/misc/arm/booting.txt (which
interestingly didn't mention uImage).
I agree.
- Ayan
Cheers,
