Re: AW: [ECOS] cat zImage >/dev/mtd1 does not work

[Gary Thomas <gary@mlbassoc.com>]

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Weiguang Shi wrote:
> Gary,
> 
> I'm at the point to flash the modified partition back but can't erase the
> FIS partition /dev/mtd4
> 
>    # cat /proc/mtd
>    dev:    size   erasesize  name
>    mtd0: 00080000 00020000 "RedBoot"
>    mtd1: 00100000 00020000 "kernel"
>    mtd2: 00200000 00020000 "ramdisk"
>    mtd3: 00020000 00020000 "kiyon_config"
>    mtd4: 0001f000 00020000 "FIS directory"
>    mtd5: 00001000 00020000 "RedBoot config"
>    # eraseall /dev/mtd4
>    eraseall: /dev/mtd4: Permission denied
> 
> I realized that I may need to "unlock" it but both my attempts to do that
> in RedBoot and Linux failed. In the former, "fis unlock" worked fine in 
> Redboot but after Linux boots up I still get the same "Permission denied"
> error. In linux, my unlock resulted in 
>         # unlock /dev/mtd4
>         Could not open mtd device: /dev/mtd4
>         # unlock /dev/mtd5
>         Could not open mtd device: /dev/mtd5
> 
> Any ideas on how shall I proceed?

The problem is that if you use combined FIS directory and FCONFIG data
(which you are based on the map above), then the MTD layer makes both of
those images read only.  The attached patch can let you override this.
It's based on the public 2.6.18 kernel.

Note: you need to be careful doing these changes to your FLASH.  If you
simply erase the partition, RedBoot will lose everything.  MTD is pretty
cool and if you simply open /dev/mtd4 read/write, read the current contents,
update them and then rewrite them, the MTD layer will take care of erasing
and updating the appropriate portions.

> --- Gary Thomas <gary@mlbassoc.com> wrote:
> 
>> Weiguang Shi wrote:
>>> That's even better and was the solution that I was looking for.
>>> The question is how, from the OS, can I update the FIS. Obviously
>>> I need to know the structure of the "FIS directory" partition and
>>> find the offset of that checksum and insert a '0' there by 
>>>    - reading the whole partition into ram, 
>>>    - changing the bit, erasing the partition on the flash, 
>>>    - and finally flashing the modified partition in the ram back.
>>>
>>> Any suggestions as to where to start?
>> <redboot/fis.h>
>>
>> Also, drivers/mtd has some RedBoot FIS parsing code in it.  You could
>> look at it for pointers.
>>
>>> --- Gary Thomas <gary@mlbassoc.com> wrote:
>>>
>>>> Note: you don't really need to change RedBoot.  Just update the
>>>> FIS [directory] entry for the image you are changing, either with
>>>> the corrected checksum, or the value 0.  RedBoot ignores the checksum
>>>> when the stored value is 0.

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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diff -ubNr --exclude=.gitignore linux-2.6.18/drivers/mtd/redboot.c /tmp/fc_base/opt/amltd/develop/linuxppc-2.6/drivers/mtd/redboot.c
--- linux-2.6.18/drivers/mtd/redboot.c	2006-09-19 21:42:06.000000000 -0600
+++ /tmp/fc_base/opt/amltd/develop/linuxppc-2.6/drivers/mtd/redboot.c	2006-10-24 11:59:32.000000000 -0600
@@ -85,6 +85,10 @@
 
 	numslots = (master->erasesize / sizeof(struct fis_image_desc));
 	for (i = 0; i < numslots; i++) {
+                if (buf[i].name[0] == 0xff) {
+                        i = numslots;
+                        break;
+                }
 		if (!memcmp(buf[i].name, "FIS directory", 14)) {
 			/* This is apparently the FIS directory entry for the
 			 * FIS directory itself.  The FIS directory size is
@@ -124,7 +128,7 @@
 		struct fis_list *new_fl, **prev;
 
 		if (buf[i].name[0] == 0xff)
-			continue;
+                        break;
 		if (!redboot_checksum(&buf[i]))
 			break;
 
@@ -196,14 +200,22 @@
 		parts[i].size = fl->img->size;
 		parts[i].offset = fl->img->flash_base;
 		parts[i].name = names;
-
 		strcpy(names, fl->img->name);
+
 #ifdef CONFIG_MTD_REDBOOT_PARTS_READONLY
 		if (!memcmp(names, "RedBoot", 8) ||
 				!memcmp(names, "RedBoot config", 15) ||
 				!memcmp(names, "FIS directory", 14)) {
 			parts[i].mask_flags = MTD_WRITEABLE;
 		}
+#else
+		if (!memcmp(names, "FIS directory", 14)) {
+                    // Special hack to let directory be read/write
+                    if ((fl->img->size & (master->erasesize - 1)) != 0) {
+                        parts[i].size = (fl->img->size + (master->erasesize - 1)) & ~(master->erasesize - 1);
+                    }
+                }
+
 #endif
 		names += strlen(names)+1;
 


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