[LinuxBIOS] RFC Winflashrom Architecture -- Current device driver (testbed)

Peter Stuge stuge-linuxbios at cdy.org
Wed Jun 6 18:25:13 CEST 2007

On Wed, Jun 06, 2007 at 11:16:03PM +0700, Darmawan Salihun wrote:
> > 1. Kernel driver allowing unrestricted reads and writes to top 16MB.
> The current version of the driver code is capable of mapping
> *anywhere* within the 4GB physical address space. It shouldn't be a
> problem to restrict it to the top 16MB.

We should make that 2MB until we actually support larger flash parts

> The logic of the mapping process is as follows:
>  a. The physical memory address range is mapped into the kernel's
> virtual memory address range
> b. The kernel's virtual memory address range is then mapped to the
> "requesting" user mode virtual memory address range.

Sounds good.

> > 2. Kernel driver implementing the lowest level flash chip API.
> >  Possibly using some macro language so that reboot isn't neccessary
> >  to upgrade flash support.
> Can you please elaborate more on this idea?

Still a hard limit of 2MB space in the kernel driver.

The application would "upload" a protocol description to the kernel
driver so that the kernel driver does not have to change just because
timing parameters or special byte values used in programming
sequences change for a newly added flash chips. In practise this idea
may turn out to allow just as much damage as (1) and in that case we
should just stick with (1).


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