Re: [PATCH v2] tools: implement initial ramdisk support for ARM.

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

On 04/08/2014 06:29 PM, Julien Grall wrote:
> Hi Ian & Ian,
> 
> On 04/08/2014 05:53 PM, Ian Jackson wrote:
>> Ian Campbell writes ("Re: [PATCH v2] tools: implement initial ramdisk support for ARM."):
>>> On Fri, 2014-04-04 at 16:00 +0100, Ian Jackson wrote:
>>>> I think this is a viable backport candidate.  Can you let me know when
>>>> it's in-tree and I'll add it to my list
>>>
>>> It's in now, commit 314c9815e2f5dc8a9fec11e0cf9b49b16ed0e96b
>>
>> Noted, thanks.
> 
> I'm unable to boot a guest with this patch on Xen 4.5. Revert it works
> correctly. The guest is blocked without useful log.
> 
> My config:
> 
> kernel="/root/zImage"
> memory=128
> name="test"
> vcpus=2
> autoballon="off"
> root="/dev/xvda"
> extra="console=hvc0"
> disk=[ 'phy:/dev/loop0,xvda,w' ]
> 

This small changes fix boot of the guest with RAM < 128Mb:

diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
index f051515..2228ba5 100644
--- a/tools/libxc/xc_dom_arm.c
+++ b/tools/libxc/xc_dom_arm.c
@@ -300,7 +300,7 @@ int arch_setup_meminit(struct xc_dom_image *dom)
     if ( ramend >= ram128mb + modsize && kernend < ram128mb )
         modbase = ram128mb;
     else if ( ramend >= kernend + modsize )
-        modbase = kernend;
+        modbase = ramend - modsize;
     else
         return -1;

I guess this is because the kernel is extracting on it. I think we
should follow the same "algorithm" as Xen (see place_modules) to decide
where the modules should be loaded.

Regards,

-- 
Julien Grall