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b2ad4722e9
Waiting a full second is a very long time, especially when
default_delay() chooses to busy-loop. This code has been around for a
decade, with vague references to user reports:
commit 8ab49e72af8465d4527de2ec37b22cd44f7a1169
Date: Wed Aug 19 13:55:34 2009 +0000
Disallow erase/write for known bad chips so people won't try without a clear understanding
Still, this logic does not belong in the high-level library logic, used
by all programmers and all chips. If there is a timing issue, it should
either be encoded in the appropriate programmer or flashchip timing.
However, we don't really know what chips were in use, as the above
commit doesn't have any links to reports. So in a feeble attempt at
avoiding breaking users here, we also surmise that...
* SPI chips weren't all that common in 2009;
* I'm mostly motivated by flashrom performance on Chromebooks, were SPI
chips (and linux_mtd / BUS_PROG) are the rule; and
* SPI chips have precise timing requirements and an appropriate BUSY
status. So we guess that this "calm down" magic delay wouldn't be
necessary there.
Thus, we allow this magic delay only on non-SPI (and non-BUG_PROG, used
by linux_mtd for one) buses as a compromise.
Now, this change has some (hopefully [1] tiny) chance of regression, so
we have the following considerations:
1. emergency_help_message() already provides documentation on how to
contact support, in case we need to handle any user-reported
regressions.
2. If there is any regression here, it's only in the --verify code; so
we can always provide workarounds for testing this, to determine
whether this change may have been at fault. For example, something
like:
flashrom --write /my/new/image.bin --noverify
sleep 1
flashrom --read /tmp/bar.bin
cmp /my/new/image.bin /tmp/bar.bin
If such problems occur, we can collect system/programmer/chip info to
try to encode a more targeted delay into the appropriate
chip/programmer implementation, and avoid penalizing the entire
project like this.
3. We already have (embedded in erase_write()) erase verification that
performs no such delay. So depending on the type of timing error that
this delay was attempting to cover, we may have some proof that this
delay is no longer necessary (or at least, that whatever systems were
needing this delay in the first place are no longer caring about
flashrom).
4. We've retained the delay for buses that were likely common in 2009
(per the above "feeble attempt").
NB: I avoid using the BUS_NONSPI macro, because I want to exclude any
future buses from this workaround, even in the event that the BUS_NONSPI
category grows in the future.
[1] Famous last words.
BUG=b:325539928
TEST=`flashrom_tester --flashrom_binary=$(which flashrom) \
internal Erase_and_Write Fail_to_verify`,
TEST=`vpd -i RW_VPD -s foo=bar; vpd -i RW_VPD -l; \
vpd -i RW_VPD -d foo; vpd -i RW_VPD -l`
TEST=`elogtool list; elogtool add 0xa7; elogtool list`
on (at least) 2 systems:
#1: Kukui/Kakadu rev2 - MTD programmer /
kernel 5.10.215-24542-g0515a679eb42 /
CrOS ~ 15857.0.0
#2: Zork/Dirinboz rev2 -
chip name: vendor="Winbond" name="W25Q128.JW.DTR" /
BIOS: Google_Dirinboz.13434.688.0 /
kernel 5.4.267-21940-g67f70e251a74 /
CrOS ~ 15753.43.0
Change-Id: Ie09651fede3f9f03425244c94a2da8bae00315fc
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/80807
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
flashrom README
===============
flashrom is a utility for detecting, reading, writing, verifying and erasing
flash chips. It is often used to flash BIOS/EFI/coreboot/firmware images
in-system using a supported mainboard, but it also supports flashing of network
cards (NICs), SATA controller cards, and other external devices which can
program flash chips.
It supports a wide range of flash chips (most commonly found in SOIC8, DIP8,
SOIC16, WSON8, PLCC32, DIP32, TSOP32, and TSOP40 packages), which use various
protocols such as LPC, FWH, parallel flash, or SPI.
Do not use flashrom on laptops (yet)! The embedded controller (EC) present in
many laptops might interact badly with any attempts to communicate with the
flash chip and may brick your laptop.
Please make a backup of your flash chip before writing to it.
Please see the flashrom(8) manpage :doc:`classic_cli_manpage`.
Building / installing / packaging
---------------------------------
flashrom supports building with **make** and **meson**.
TLDR, building with meson
"""""""""""""""""""""""""
::
meson setup builddir
meson compile -C builddir
meson test -C builddir
meson install -C builddir
For full detailed instructions, follow the information in
:doc:`dev_guide/building_from_source`
TLDR, building with make
""""""""""""""""""""""""
::
make
make install
For full detailed instructions, follow the information in
:doc:`dev_guide/building_with_make`
Contact
-------
The official flashrom website is:
https://www.flashrom.org/
For available contact methods see :doc:`contact`