Hi,
On 10/30/18 3:58 PM, Ian Jackson wrote:
Stefano Stabellini writes ("[PATCH v8 7/8] xen/arm: export shared memory regions as
reserved-memory on device tree"):
Shared memory regions need to be advertised to the guest. Fortunately, a
device tree binding for special memory regions already exist:
reserved-memory.
Oh! Here is the guest ABI.
But it's not documented.
Device-Tree bindings are documented in
linux/Document/device-tree/bindings. Stefano sent it via the DT mailing
list (see [1]).
Stefano, would you mind to add a pointer in the commit message?
diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
index 054ad58..c1624c0 100644
--- a/tools/libxl/libxl_arm.c
+++ b/tools/libxl/libxl_arm.c
@@ -436,6 +436,58 @@ static int make_memory_nodes(libxl__gc *gc, void *fdt,
return 0;
}
+static int make_reserved_nodes(libxl__gc *gc, void *fdt,
+ libxl_domain_config *d_config)
+{
+ int res, i;
+ const char *name;
+
+ if (d_config->num_sshms == 0)
+ return 0;
+
+ res = fdt_begin_node(fdt, "reserved-memory");
+ if (res) return res;
+
+ res = fdt_property_cell(fdt, "#address-cells", GUEST_ROOT_ADDRESS_CELLS);
+ if (res) return res;
+
+ res = fdt_property_cell(fdt, "#size-cells", GUEST_ROOT_SIZE_CELLS);
+ if (res) return res;
+
+ res = fdt_property(fdt, "ranges", NULL, 0);
+ if (res) return res;
The line lengths here are very long.
They should still be under 75-80 characters a line has mandated per the
coding style. Is that an issue?
Also it's quite formulaic. I
see make_psci_node is quite like that too. IDK whether a local macro
would help.
Possibly, but that not really related to this patch itself. Can we look
that as a clean-up?
+ for (i = 0; i < d_config->num_sshms; i++) {
+ uint64_t start = d_config->sshms[i].begin;
+
+ if (d_config->sshms[i].role == LIBXL_SSHM_ROLE_SLAVE)
+ start += d_config->sshms[i].offset;
Why is d_config->sshms[i].offset not 0 for the owner ?
You could do this unconditionally.
From the documentation:
"Can only appear when B<role> = slave. If set, the address mapping will
not start from the beginning the backing memory region, but from the middle
(B<offset> bytes away from the beginning) of it. See the graph below:
With B<offset> = 0, the mapping will look like:
backing memory region: #########################################
| |
| |
| |
V V
slave's shared region: #########################
With B<offset> > 0:
backing memory region: #########################################
|<-- offset -->|| |
| |
| |
V V
slave's memory region: #########################
"
This allows the configuration in the owning domain to be simpler as you
can share a big region and split between multiple domain.
-static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_build_info *info,
+static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_config *d_config,
Can we have this NFC change and its consequences as a pre-patch ?
Cheers,
[1] https://lists.xen.org/archives/html/xen-devel/2018-10/msg01812.html
--
Julien Grall
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