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SubjectRe: [PATCH] of/fdt: add kernel command line option for dtb_compat string
On Wed, Dec 22, 2010 at 12:04:56PM -0800, Dirk Brandewie wrote:
> On 12/06/2010 09:54 AM, dirk.brandewie@gmail.com wrote:
> >From: Dirk Brandewie<dirk.brandewie@gmail.com>
> >
> >Adds a kernel command line option "dtb_compat=<string>". This string
> >will be used to select the first compatible device tree blob linked
> >into the kernel if a device tree blob is was *not* passed in by the
> >bootloader.
> >
> >Signed-off-by: Dirk Brandewie<dirk.brandewie@gmail.com>
> >---
> > Documentation/kernel-parameters.txt | 8 ++++++
> > drivers/of/fdt.c | 48 +++++++++++++++++++++++++++++++++++
> > 2 files changed, 56 insertions(+), 0 deletions(-)
> >
> >diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> >index 92e83e5..64093e5 100644
> >--- a/Documentation/kernel-parameters.txt
> >+++ b/Documentation/kernel-parameters.txt
> >@@ -655,6 +655,14 @@ and is between 256 and 4096 characters. It is defined in the file
> >
> > dscc4.setup= [NET]
> >
> >+ dtb_compat= [KNL]
> >+ Specify the "compatible" string for the device
> >+ tree blob present in the vmlinux image. This
> >+ string will be used to select the first device
> >+ tree blob whose compatible property matches
> >+ the string if a dtb was NOT passed in by the
> >+ bootloader.
> >+
> > dynamic_printk Enables pr_debug()/dev_dbg() calls if
> > CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
> > These can also be switched on/off via
> >diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> >index c1360e0..ca1318c 100644
> >--- a/drivers/of/fdt.c
> >+++ b/drivers/of/fdt.c
> >@@ -15,6 +15,8 @@
> > #include<linux/of_fdt.h>
> > #include<linux/string.h>
> > #include<linux/errno.h>
> >+#include<asm-generic/vmlinux.lds.h>
> >+
> >
> > #ifdef CONFIG_PPC
> > #include<asm/machdep.h>
> >@@ -604,3 +606,49 @@ void __init unflatten_device_tree(void)
> >
> > pr_debug("<- unflatten_device_tree()\n");
> > }
> >+
> >+extern uint8_t __dtb_start[];
> >+extern uint8_t __dtb_end[];
> >+static void __init *of_flat_dt_find_compatible_dtb(char *name)
> >+{
> >+ void *rc = NULL;
> >+ unsigned long root, size;
> >+ struct boot_param_header *orig_initial_boot_params;
> >+ uint8_t *blob;
> >+
> >+ orig_initial_boot_params = initial_boot_params;
> >+ blob = __dtb_start;
> >+ initial_boot_params = (struct boot_param_header *)blob;
> >+
> >+ while (blob< __dtb_end) {
> >+ if (be32_to_cpu(initial_boot_params->magic) != OF_DT_HEADER) {
> >+ WARN(1, "Invalid device tree blob in vmlinux\n");
> >+ break;
> >+ }
> >+
> >+ root = of_get_flat_dt_root();
> >+ if (of_flat_dt_is_compatible(root, name)> 0) {
> >+ rc = blob;
> >+ break;
> >+ }
> >+
> >+ size = be32_to_cpu(initial_boot_params->totalsize);
> >+ blob = PTR_ALIGN(blob + size, STRUCT_ALIGNMENT);
> >+ initial_boot_params = (struct boot_param_header *)blob;
> >+ }
> >+
> >+ if (rc == NULL)
> >+ initial_boot_params = orig_initial_boot_params;
> >+ return rc;
> >+}
> >+
> >+
> >+static int __init of_flat_dtb_compat_setup(char *line)
> >+{
> >+ if (!initial_boot_params)
> >+ initial_boot_params = of_flat_dt_find_compatible_dtb(line);
> >+ return 1;
> >+}
> >+
> >+early_param("dtb_compat", of_flat_dtb_compat_setup);
> >+
> Any more comments on this patch? Is it good to go or DOA?

Not DOA, but I want to discuss the linking vs. wrapper issue again
before I commit to merging it. BTW, sorry for being MIA on this stuff
for pretty much all December. I got over committed, but things should
be better now.

g.



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