AW: [ECOS] cat zImage >/dev/mtd1 does not work
Gary Thomas
gary@mlbassoc.com
Tue Jan 23 08:42:00 GMT 2007
Weiguang Shi wrote:
> Thanks again.
>
> My system is 2.4.x under snapgear-3.4.0 and I applied only the following part of the patch
> since this only seems to be relevant.
>
> #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);
> }
> }
>
>
> When I tried to cat the modified ram image for the FIS partition back to /dev/mtd4
> I still get
>
> cat: Write Error: Read-only file system
You missed the part of the patch that allows the FIS directory to be
writable even if you have combined FIS & FCONFIG. I don't have such an
old system, so you'll need to figure out how to get that code in.
> --- Gary Thomas <gary@mlbassoc.com> wrote:
>
>> 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
>> ------------------------------------------------------------
>>> 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;
>>
>>
>>> --
>> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
>> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
>
>
>
>
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--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
--
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