Re: [Xen-devel] [PATCH] xen/arm: flush dcache after memcpy'ing the kernel image

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-12-18 at 18:51 +0000, Stefano Stabellini wrote:
> On Thu, 6 Dec 2012, Ian Campbell wrote:
> > On Wed, 2012-12-05 at 18:37 +0000, Stefano Stabellini wrote:
> > > After memcpy'ing the kernel in guest memory we need to flush the dcache
> > > to make sure that the data actually reaches the memory before we start
> > > executing guest code with caches disabled.
> > > 
> > > This fixes a boot time bug on the Cortex A15 Versatile Express that
> > > usually shows up as follow:
> > > 
> > > (XEN) Hypervisor Trap. HSR=0x80000006 EC=0x20 IL=0 Syndrome=6
> > > (XEN) Unexpected Trap: Hypervisor
> > 
> > That's a symptom of a thousand different problems though, since it's
> > just a generic Instruction Abort from guest mode caused by a translation
> > fault at stage 2. 
> > 
> > Anyhow this won't apply in top of "arm: support for initial modules
> > (e.g. dom0) and DTB supplied in RAM", could you rebase on that please?
> 
> The patch applies fine on both xen/master and xen/staging.
> 
> Do you have a branch with "arm: support for initial modules (e.g. dom0)
> and DTB supplied in RAM" somewhere?

I do now:
        git://xenbits.xen.org/people/ianc/xen-unstable.git boot-wrapper
        
You had some comments on the DTB parsing/filtering which I replied to.

Perhaps I should reorder the series to put the useful infrastructure
first (so it can be pushed) but leave the actual concrete DTB interface
until the end. The DTB stuff is really a PoC pending a real bootloader
protocol and if no modules are given (which is what it will look like if
we omit that bit) then Xen should fallback to the current method of
looking in the flash for the kernel.

I think that would mean ordering this series as:

[PATCH 1/9] xen: arm: mark early_panic as a noreturn function
<bits of 2/9 which define the datastructures, but not the parsing stuff>
[PATCH 3/9] arm: avoid placing Xen over any modules.
<patches 4..8>
[PATCH 2/9] xen: arm: parse modules from DT during early boot.
[PATCH 9/9] xen: strip /chosen/modules/module@<N>/* from dom0 device tree


Ian.


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