[flashrom] Hardware Sequencing vs Software Sequencing

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Tue Mar 30 03:19:00 CEST 2010

Hi John,

On 30.03.2010 02:47, john warwick wrote:
> I was looking through the code, and see that flashrom is using software sequencing. Is there any reason for software sequencing to be chosen instead of hardware sequencing?

Assuming that you're talking about the Intel ICH SPI code, here's the
info I have:
Yes, there are multiple reasons why hardware sequencing is not supported:
- You can't reflash the complete chip, just the region for the current
(BIOS) descriptor.
- You're unable to read the whole chip.
- If you exchange the flash chip, write/erase may fail in random ways.
- Crossflashing/hotflashing is pretty much impossible.
- Nobody implemented it.

> Are there any restrictions imposed for hardware sequencing?

Please see above.

Of course, if you're willing to contribute code for ICH SPI hardware
sequencing, we'll be glad to review and merge it. Please be warned that
this is a rather difficult task, especially because flashrom assumes
that a flash chip can be accessed in full and you'll either have to
emulate this or change flashrom safety checks and code flow in a few
strategic places.



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