[U-Boot] FAT filesystem support on SPI flash
Hi, On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I have not found existing U-Boot support for such functionality. Have I missed it?
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I note about design: As our chip (TI's AM335x) does not support direct boot from FAT stored on SPI, I plan reserving section at the beginning of SPI flash for the first stage boot loader and having the filesystem after it.
Best, Vasili
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Dear Vasili,
In message d69e639dbb744e9ca4c7742f42c82b81@EX13.visionmap.co.il you wrote:
On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I have not found existing U-Boot support for such functionality. Have I missed it?
We do not have FAT suppot on flash devices yet.
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I think the best way to implement this would require a two staged approach: in the first stage, U-Boot should adapte the device driver model we've been waiting for so long; in the second stage, the file system support would more or less fall into place on to of the then existing storage device drivers.
Best regards,
Wolfgang Denk
Dear Wolfgang,
1. So, my understanding is that fatload/fatls/etc have only MMC/SATA support now? No support for MTD?
2. Where can I find the description of "device driver model" you mention? When is it planned to be adopted?
Best, Vasili
On Sun, Feb 23, 2014 at 7:23 PM, Wolfgang Denk wd@denx.de wrote:
Dear Vasili,
In message d69e639dbb744e9ca4c7742f42c82b81@EX13.visionmap.co.il you wrote:
On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I have not found existing U-Boot support for such functionality. Have I missed it?
We do not have FAT suppot on flash devices yet.
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I think the best way to implement this would require a two staged approach: in the first stage, U-Boot should adapte the device driver model we've been waiting for so long; in the second stage, the file system support would more or less fall into place on to of the then existing storage device drivers.
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de When some people discover the truth, they just can't understand why everybody isn't eager to hear it.
On Sun, Feb 23, 2014 at 7:07 PM, Vasili Galka vasili@visionmap.com wrote:
Hi,
On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I'm not a file-system expert, but I've a basic question like how does/well a SPI flash(mtd) device have FAT support on it. Generally flash file-systems were categories to do the job right?
I have not found existing U-Boot support for such functionality. Have I missed it?
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I note about design: As our chip (TI's AM335x) does not support direct boot from FAT stored on SPI, I plan reserving section at the beginning of SPI flash for the first stage boot loader and having the filesystem after it.
thanks!
Dear Jagan,
I'm not sure I fully understand your question. SPI flash is just a medium that has sectors/pages/blocks (call it however you want). You are free to store data with any structure you like on it. So if you like - you can store FAT file-system on it. That's true that maybe storing a FAT file-system that has frequent write operations on SPI flash is not a good idea, both because of speed and because of flash wear. But that is an entirely different question. There are still many cases when the data does not change frequently and FAT on SPI flash can be useful.
Best, Vasili
On Sun, Feb 23, 2014 at 7:49 PM, Jagan Teki jagannadh.teki@gmail.com wrote:
On Sun, Feb 23, 2014 at 7:07 PM, Vasili Galka vasili@visionmap.com wrote:
Hi,
On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I'm not a file-system expert, but I've a basic question like how does/well a SPI flash(mtd) device have FAT support on it. Generally flash file-systems were categories to do the job right?
I have not found existing U-Boot support for such functionality. Have I missed it?
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I note about design: As our chip (TI's AM335x) does not support direct boot from FAT stored on SPI, I plan reserving section at the beginning of SPI flash for the first stage boot loader and having the filesystem after it.
thanks!
Jagan.
On Sun, Feb 23, 2014 at 01:37:53PM +0000, Vasili Galka wrote:
Hi,
On our system, we are interested in keeping all files, including the OS image and U-Boot second stage on FAT filesystem residing on a SPI flash.
I have not found existing U-Boot support for such functionality. Have I missed it?
In any case, I'm willing to implement this, do you see it reasonable incorporating such code into U-Boot? (if it passes review of course)
I note about design: As our chip (TI's AM335x) does not support direct boot from FAT stored on SPI, I plan reserving section at the beginning of SPI flash for the first stage boot loader and having the filesystem after it.
The high level suggestion is to review your design decision as this seems rather questionable. Today our FAT code doesn't work directly on flash, but I imagine a day or two of hacking might allow it to work. But FAT isn't designed to be on flash directly and you really want a good reason to not be using a flash filesystem on SPI.
participants (5)
-
Jagan Teki -
Tom Rini -
Vasili Galka -
Vasili Galka -
Wolfgang Denk