[flashrom] [PATCH 1/1] Add support for reading the current flash contents from a file

[Michael Karcher]

On 04/19/2016 10:18 PM, Carl-Daniel Hailfinger wrote:

> You're introducing a new toplevel parameter for this, and I wonder
> whether it would make more sense to handle it as a programmer option.
> The dummy programmer supports reading in emulated flash chip content on
> startup and writing out emulated flash chip content on shutdown, all
> specified with -p dummy:emulate=M25P10.RES,image=foobar.bin
>
> For consistency reasons, we should make sure that supplying assumed chip
> contents works as designed both for hardware-based programmers as well
> as the dummy programmer.
> I don't have a strong preference for -C or -p foobar:image=some.bin, and
> would like to hear what others think.
I strongly prefer a standalone toplevel option, as the feature is
programmer independent. Of course, this means that for the dummy
programmer we now have -C and -p image=some.bin. I don't consider it a
bad thing, but a good thing. An important use case for the dummy
programmer is to test flashrom under various conditions. This might be
flashrom getting "-C" with the contents of the chip, or flashrom getting
no "-C" and reading first. Both execution flows should be testable using
the dummy programmer.
On the other hand, separate options allow mismatch of "-C" and the image
file specified in "-p dummy:image=some.bin". Specifying wrong chip
contents is an undesireable situation one really wants to avoid in
practice, because it causes flashrom to do unpredictable things. In my
oppinion, we should nevertheless support getting into this situation
with the dummy programmer, as we are equally able to get into that
situation with real programmers.
Yet a way to avoid the mismatch seems a good thing to have, too. So I
suggest to have "-C" load the "actual contents" of the chip
independently from any programmer option or any programmer code, but
make it possible for the dummy programmer to initialize the emulated
flash chip from the loaded "actual contents". Something like -p
dummy:autoimage comes to my mind, although I understand that loading the
"-C" can well be performed after programmer initialization, but
initializing the emulated dummy flash chip is done during programmer
initialization. I still tend to work around that in code (i.e. having
the -C load before programmer init, even if it complicates the
read/erase/program/verify logic).

Regards,
  Michael Karcher