Hi there, On Sun, Mar 1, 2026 at 5:47 AM Abdelkader Boudih <[email protected]> wrote:
> Hi, > > I would like to propose a small CLI addition: --verify-reads[=<count>]. > > When reading flash over an external programmer, a single successful read > is not proof the data is correct (i learned the lesson when i lost bios > original). > > This is particularly common with: > > - Clip-on programmers (Pomona, SOIC8 clips) where contact pressure varies > and pins may not seat fully on all pads simultaneously > - Budget CH341A/CH347 adapters with cheap ZIF sockets. > - Long or unshielded SPI wiring picking up noise > > in these situations the programmer reports success, the read completes > without error, but individual bytes or ranges are silently wrong due to > marginal signal integrity. The only current mitigation is to read multiple > times manually and compare with sha256sum. > > --verify-reads[=<count>] reads the flash count times (default: 3, min: 2) > and compares consecutive reads byte-by-byte. On mismatch it reports the > offset and the two differing read numbers. > Note that flashrom already has a `-v` / `--verify` command, which compares the contents of a flash chip with the provided file. In my experience I've found it to be good enough in most cases. After all, my read integrity problems have mostly been about reading a chip and verifying that the read matches the chip's contents, but turns out that the read data is nonsense (e.g. all FFs). So these days I check if the dump I've just taken looks right; e.g. after reading a mainboard's flash chip (where UEFI is stored), I check that UEFITool can open it. > Consecutive comparison is used deliberately rather than comparing all > reads against read first read. > > A patch is ready. Happy to Gerrit it if the approach looks reasonable, or > adjust based on feedback. > Please don't hesitate and simply put it up on Gerrit. The point of Gerrit is to review and discuss patches, after all! :-) > Abdelkader Boudih > _______________________________________________ > flashrom mailing list -- [email protected] > To unsubscribe send an email to [email protected] > Best regards, Angel
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