First RSPRO deployed !

[Adrian Chadd]

Nah, the problem is:

* the large, fixed blocksize that the current flash code has;
* ffs isn't really optimised for this kind of flash;
* this kind of flash is will not like constant 4k erase cycles, which
is unfortunately what you'll end up with.

My current path forward is:

* aim to get geom_ulzma into the base :-)
* modify it a bit so it exports two GEOM devices - a read-only device
with the lzma'ed FS in it, and a read-write'able "rest";
* modify GEOM to pass through disk parameters from the provider, so
the flash device can export attributes (read size, write sizes, etc);
* modify the flash driver to have a small default block size (say, 128
bytes) so small transactions don't require huge amounts of SPI bus
access;
* experiment with a simple append-only flash FS, which mounts on top
of a read-only base filesystem.

This mirrors what the flash device/fs stuff in linux does to some
extent. The "rootfs" partition has a read only bit. Any filesystem
modifications happen in the read-write part -after- that. If the user
wants, they can simply erase the rootfs part -after- the read-only
lzma'ed FFS partition, giving them a clean "default" system.

If someone else wants to give this a go, be my guest. :-)


Adrian

On 19 November 2010 19:06, Monthadar Al Jaberi <monthadar at gmail.com> wrote:
> On Fri, Nov 19, 2010 at 12:01 PM, Milan Obuch <freebsd-mips at dino.sk> wrote:
>> On Thursday 18 November 2010 13:43:51 Monthadar Al Jaberi wrote:
>>> OMG, thank you Luiz for the file.... Adrian forgot to mention that you
>>> need to add kern_memstart field to the fw_layout_data structure!!!
>>>
>>> Its works...so I guess to boot from flash we need to play with the
>>> flash driver and ffs... thats a totally different story though :P
>>>
>>
>> Well, with mkfwimage it is possible to write FreeBSD into flash on RSPRO and
>> boot from it. I just verified this. Using it the way it's used in mkflash
>> script has one drawback, I think - your setup is static and you are not using
>> whole flash to its best potential as well. Actually, with patches you are able
>> to read flash (verified) and probably write to it, too, so the 'only'
>> remaining part is ffs tuned to use it...
>
> mm, as I understood it it should be easy for ffs2 to work, just need
> to fix some macros so that the code that probes for the superblock
> work...
> reading/writting to flash with correct sectorsize is no problem....
>
>>
>> Regards,
>> Milan
>>
>
>
>
> --
> //Monthadar Al Jaberi
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