I changed my local copy of the flashrom trunk to never set the write-enable-bit. Then, on the target machine, I double-checked with lspci that the bit isn't set. Next, I called "flashrom -w bios.bin" to let it try & write to the flash chip.
As a result, I got flashrom errors, telling me that it couldn't erase the chip:
Erasing and writing flash chip contents... Transaction error! spi_block_erase_20 failed during command execution at address 0xe3000 ... spi_block_erase_52 failed during command execution at address 0xe3000 ... spi_block_erase_d8 failed during command execution at address 0xe0000 ... spi_block_erase_60 failed during command execution ... spi_block_erase_c7 failed during command execution ... FAILED! Uh oh. Erase/write failed. Checking if anything changed. Good. It seems nothing was changed. Writing to the flash chip apparently didn't do anything.
Furthermore, a colleague told that they actually once have read the SPI accesses with a osci, and that no write / erase cycles have been executed without this bit set (sry don't have proof for that right now).
Es gelten unsere Allgemeinen Leistungsbedingungen die unter http://www.msc-ge.com/alb abrufbar sind.
Our standard terms and conditions apply which are available under http://www.msc-ge.com/alb .
MSC Vertriebs GmbH
Sitz der Gesellschaft: Industriestrasse 16, 76297 Stutensee Handelsregister: Mannheim, HRB Nr. 10 3631 Geschäftsführung: Manfred Schwarztrauber, Lothar Kümmerlin, Rüdiger Kuhn, Silvano Geissler Umsatzsteuer ID Nr.: DE 143 585 507 WEEE Reg. Nr. : DE 31011852
Gleichmann & Co. Electronics GmbH
Sitz der Gesellschaft: Schraderstrasse 44, 67227 Frankenthal Handelsregister: Ludwigshafen, HRB Nr. 21305 Geschäftsführung: Manfred Schwarztrauber, Thomas Klein Umsatzsteuer ID Nr. : DE 148 421 329 WEEE Reg. Nr.: DE 72277043
Diese E-Mail enthält vertrauliche und/ oder rechtlich geschützte Informationen. Wenn Sie nicht der beabsichtigte Empfänger sind, informieren Sie bitte sofort den Absender und löschen Sie diese E-Mail.
The information contained in this message is confidential and/ or protected by law. If you are not the intended recipient, please contact the sender and delete this message.
-----Ursprüngliche Nachricht----- Von: Stefan Tauner [mailto:stefan.tauner@student.tuwien.ac.at] Gesendet: Mittwoch, 14. September 2011 14:03 An: Feldschmid, Ingo Cc: flashrom@flashrom.org Betreff: [SPAM?]Re: [flashrom] [PATCH] revamp the warning of failing to set BIOS write enable in enable_flash_ich
On Wed, 14 Sep 2011 13:51:04 +0200 "Feldschmid, Ingo" ifel@msc-ge.com wrote:
I checked with some boards with different Intel chipsets (some ICHx and Tunnel Creeks), and the bios write enable bit does affect the SPI bus. It will quite likely be ignored for PCI accesses, but everything that goes through the chipset is affected by this bit. So if this bit is not set, write accesses to the bios flash will not be clocked to the SPI bus.
what have you "checked" exactly? did you try clearing the bit, issuing SPI commands and looked at the physical bus? it's a pity that the public data sheets do not provide a clear statement regarding this bit.