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Re: [Xen-devel] [PATCH v4 3/7] xen/arm: keep track of reserved-memory regions
On Wed, 7 Aug 2019, Julien Grall wrote:
> Hi Stefano,
>
> On 06/08/2019 22:49, Stefano Stabellini wrote:
> > As we parse the device tree in Xen, keep track of the reserved-memory
> > regions as they need special treatment (follow-up patches will make use
> > of the stored information.)
> >
> > Reuse process_memory_node to add reserved-memory regions to the
> > bootinfo.reserved_mem array.
> >
> > Refuse to continue once we reach the max number of reserved memory
> > regions to avoid accidentally mapping any portions of them into a VM.
> >
> > Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> >
> > ---
> > Changes in v4:
> > - depth + 1 in process_reserved_memory_node
>
> Ah, you fixed it in this patch. But then, this does not match the
> documentation in patch #1.
Yes good point, see below
> > - pass address_cells and size_cells to device_tree_for_each_node
> > - pass struct meminfo * instead of a boolean to process_memory_node
> > - improve in-code comment
>
> I can't see any comment, is that an improvement? :)
It got lost with the refactoring of the code, but I don't think we need
it anymore
> > - use a separate process_reserved_memory_node (separate from
> > process_memory_node) function wrapper to have different error handling
> >
> > Changes in v3:
> > - match only /reserved-memory
> > - put the warning back in place for reg not present on a normal memory
> > region
> > - refuse to continue once we reach the max number of reserved memory
> > regions
> >
> > Changes in v2:
> > - call process_memory_node from process_reserved_memory_node to avoid
> > duplication
> > ---
> > xen/arch/arm/bootfdt.c | 43 +++++++++++++++++++++++++++++++------
> > xen/include/asm-arm/setup.h | 1 +
> > 2 files changed, 38 insertions(+), 6 deletions(-)
> >
> > diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> > index c22d57cd72..3e6fd63b16 100644
> > --- a/xen/arch/arm/bootfdt.c
> > +++ b/xen/arch/arm/bootfdt.c
> > @@ -144,6 +144,7 @@ static int __init process_memory_node(const void *fdt,
> > int node,
> > const __be32 *cell;
> > paddr_t start, size;
> > u32 reg_cells = address_cells + size_cells;
> > + struct meminfo *mem = (struct meminfo *)data;
>
> The cast is unnecessary.
>
> The rest of the code looks good. Pending the discussion about
> device_tree_for_each_node:
>
> Acked-by: Julien Grall <julien.grall@xxxxxxx>
Thank you. I removed the cast. Also, I think that it makes more sense to
do the depth increase (depth + 1) inside the implementation of
device_tree_for_each_node instead of at the caller site, like it is done
in this patch. This would match the documentation better and is cleaner
from an interface point of view. So I'll remove the depth increase from
this patch and move it to the first patch (min_depth = depth + 1).
Well, you don't need to pass the depth at all. It is just an artificial number for libfdt to know were to stop.
We also don't need the absolute depth in any of the early FDT. The relative one is sufficient.
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