[coreboot] CBFS transition plan
kevin at koconnor.net
Wed May 6 02:44:59 CEST 2009
On Tue, May 05, 2009 at 09:13:32AM -0600, Myles Watson wrote:
> 3. PCI ROM optimization. There should be some optimization for ROMs.
> a. Possibilities:
> 1. Traverse ROM once and set a flag in devices which have ROMs
> 2. Traverse ROM and keep a list of ROMs
> 3. ....
Are you referring to the email I sent on the time SeaBIOS spent
traversing CBFS to find option roms?
I did modify SeaBIOS so that option roms scans are much faster. (The
cost is now negligible.) I accomplished this by ending the file scan
if a signature of zeros is found.
I don't think caching the list of files in the flash will work well -
even one brute force scan will take too much time on large flash
chips. Instead, I think CBFS needs to have an orderly layout of files
which doesn't require users to do a brute force scan.
I think there's a simple way to accomplish this - have cbfstool create
"null" files that contain all the empty space. Then the users of cbfs
(eg, coreboot, seabios) wouldn't need any special code - they would
skip them just like they skip over any other file.
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