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Issue 662275 link

Starred by 2 users
Status: Untriaged
Owner: ----
Cc:
█ wnhuang@chromium.org
█ dhend...@chromium.org
adurbin@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: Chrome
Pri: 3
Type: Bug



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flashrom: Preserve sections?

Project Member Reported by hungte@chromium.org, Nov 4 2016 
Simply brainstorming.

In general we encourage developers to run firmware updater which will preserve right data and check everything. But we've also seen requests for cases like "this device is dead and I want to re-image using servo".

Wondering if there's a more easy way to write firmware with more flexibility? For example,

Add a "-X (exclude)" option that we can specify flashrom to never touch given sections so it's easier to preserve VPD.

 sudo flashrom -p ft2232_spi:type=servo-v2 -w image.bin -n -V -X RO_VPD -X RW_VPD -X GBB

Comment 1 by dhend...@chromium.org, Nov 4 2016 

SGTM. Conceptually it should be a simple modification to the layout handling logic to include regions by default and exclude based on -X args.

A few rules we should clarify:
1. Exclusion (-X) shall take precedence over inclusion -i. This will allow a subregion to be excluded from a region being included, e.g. "-i RO_SECTION -X RO_VPD" will preserve RO_VPD while overwriting the rest of RO_SECTION.

2. Due to rule #1, if a user specifies a region to be excluded and subregion to be included, error out. In this case the user should not use -X, instead they should only use -i to specify the included region.

3. Excluding a region implies excluding it from verification steps.

LMK if you can think of other requirements to consider. The "Partial Reads and Writes" section on http://go/cros-flashrom might provide some ideas for use cases and how we might need to deal with them.

Comment 2 by dhend...@chromium.org, Nov 4 2016 

On second thought, rule #3 should be: Excluding a region implies verification against old content for that region in both normal and --fast-verify modes. 

Currently --fast-verify only applies to included regions, so it needs to be modified to apply to excluded regions as well.

Comment 3 by hungte@chromium.org, Nov 5 2016 

BTW, what does -x (extract) currently do?
Was it really useful?

Comment 4 by dhend...@chromium.org, Nov 7 2016

Status: Available (was: Untriaged)
Good question. It was introduced in https://chromium-review.googlesource.com/#/c/60861/

Basically it reads the whole ROM and dumps each region into individual files. I'm not sure if it's used by anything - We've had the -i region[:file] syntax for longer and tools _should_ be selectively reading regions that way since it's faster and won't leave a bunch of blobs in the filesystem.

Likely this feature is just something that was kludged in before we had the consistency that we've reached today. It might still be kinda nice for other purposes (e.g. dump all regions from a user-generated layout), but I wouldn't mind repurposing the short opt (-x) for the "exclude" option. We can leave the --extract longopt in just in case it's still useful.

Comment 5 by dhend...@chromium.org, Feb 3 2017

Owner: martinroth@chromium.org

Comment 6 by martinroth@chromium.org, Aug 18 2017

Cc: wnhuang@chromium.org
Owner: ----
Project Member

Comment 7 by sheriffbot@chromium.org, Aug 20

Labels: Hotlist-Recharge-Cold
Status: Untriaged (was: Available)
This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
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