Messages in this thread | | | Date | Sun, 9 Jul 2006 14:21:18 +0200 | From | Martin Langer <> | Subject | Re: [RFC][PATCH 1/2] firmware version management: add firmware_version() |
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On Sat, Jul 08, 2006 at 03:49:57PM +0200, Marcel Holtmann wrote: > Hi Arjan, > > > > It would be good if a driver knows which firmware version will be > > > written to the hardware. I'm talking about external firmware files > > > claimed by request_firmware(). > > > > > > We know so many different firmware files for bcm43xx and it becomes > > > more and more complicated without some firmware version management. > > > > > > This patch can create the md5sum of a firmware file. Then it looks into > > > a table to figure out which version number is assigned to the hashcode. > > > That table is placed in the driver code and an example for bcm43xx comes > > > in my next mail. Any comments? > > > > why does this have to happen on the kernel side? Isn't it a lot easier > > and better to let the userspace side of things do this work, and even > > have a userspace file with the md5->version mapping? Or are there some > > practical considerations that make that hard to impossible? > > I fully agree that we shouldn't put firmware versioning into the kernel > drivers. The pattern you give to request_firmware() can be mapped to any > file on the file system. And you also have the link to the device object > and I prefer you export a sysfs file for the version so that the helper > application loading the firmware can pick the right file.
Bcm43xx has no helper application to upload the firmware. This is done in the driver. It's RAM based hardware without a Flash-ROM. The driver has to upload the firmware in the init phase after each reset.
The driver gets a firmware file from /lib/firmware/ without knowing which version this is. It's not possible to say enable this in the driver if you find a firmware x and disable that if it's only version y. That was my motivation to start thinking about firmware versioning.
But in the meantime I think it's a security issue, too. A driver should only accept firmware files with certified checksums. I guess it would be really difficult to enter a machine by firmware hijacking. So, I'm still in hope that this is only a paranoia on my side. But it's worth to think about it.
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