On Thu, Apr 21, 2016 at 1:41 PM, Salvador Eduardo Tropea < salvador@inti.gob.ar> wrote:
Hi David:
Thanks for your comments.
El 20/04/16 a las 20:42, David Hendricks escribió:
Hello Salvador, Yes, this is a very useful feature - we've had it in the chromiumos branch for a while now :-)
I need to read your implementation. Ours is called "fast-verify" which will read and only verify portions of the flash specified with -i arguments.
What about writes? My problem is that I have a 4 MiB flash and that usually need to use 32kB from it.
Yes, it works for writes as well. Using your layout file as an example: 00000000:00007e2b fpga 00007e2c:003fffff free
If the eraseblock size is 4KB and you run *"*flashrom -p <programmer> -l layout -i fpga -w foo.bin --fast-verify*"*, chromium's flashrom will: 1. Detect the flash chip. 2. Parse the -i argument 3. Do a partial read. This is broken into a multiple steps. 3a. Determine the "required_erase_size", for example, 4KB. Right now the mechanism is crude and chooses the smallest block size that is eraseable. 3b. Align regions that are read based on required_erase_size. 0000 is already aligned, but 7e2b will be aligned up to 7fff. 3c. Read the aligned region content, which is 0000:7fff instead of 0000:7e2b, into the new content buffer. 4. Copy the new content from the "fpga" region into the new content buffer. 5. Erase and write 0000:7fff 6. Verify from 0000:7fff
Overall it looks pretty similar to what you posted. Here's the original implementation: https://chromium-review.googlesource.com/#/c/240176/ https://chromium-review.googlesource.com/#/c/240176/4. There are a couple of follow-up patches as well, in case you're interested.
One more thing to note - Be careful about interactions with the proposed patch to read the current contents of flash from a file: https://www.flashrom.org/pipermail/flashrom/2015-December/014034.html. Specifically, make sure that the aligned offsets are used for reading old content no matter if the old content is in a flash chip or a file.