Can not guess flash more than 16MB correctly

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp
Domain
embedded-iot

Research direction

Start at the guess_flash_size function and inspect how its max_size limit controls flash detection. Reproduce the two-16M-chip case, then verify that the chosen scalable configuration lets picotool recognize the full flash and that info, load, and save continue to work.

Written by the indexing model from the issue text.

Description

I designed a development board with two 16M flash chips and correctly configured the opt parameters, but picotool can only recognize 16M of space.I found an issue in the source code of guess_flash_size

    // Read at decreasing power-of-two addresses until we don't see the boot pages again
    const int min_size = 16 * PAGE_SIZE;
    const int max_size = 8 * 1024 * 1024;
    int size;
    for (size = max_size; size >= min_size; size >>= 1) {
        auto new_pages = access.read_vector<uint8_t>(FLASH_START + size, 2 * PAGE_SIZE);
        if (!std::equal(first_two_pages.begin(), first_two_pages.end(), new_pages.begin())) break;
    }
    return size * 2;

Then I change the max_size to 16x1024x1024，All the picotool functions,such as info /load/save .. can run correctly.
Considering future scalability, there should be a better configuration option to address this issue.

Dominant language
C++
Stars
999
Forks
189
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