Home > Uncategorized > Treo 680 Varnish

Treo 680 Varnish

To allow Palm to cater to carriers wanting to change the branding, Palm seem to have come up with the following.

Varnishator.prc – gets the ROM token (ROW|ATT|etc) and calls CapLib.prc

CapLib.prc – Unpacks CapPackage.zip and parses CapData.xml

Varnishator.prc is probably called after a reset, depending on the comparison of the ROM token and the CapData.xml, the splashscreens are then extracted or not. If they aren’t extracted (because the ROM token is different), then the splashscreens in TelephonyUI_CNGW_enUS.lprc are used as default.

In terms of using this behaviour to create our own custom ‘varnish’, we are probably looking at modifying the XML to match whatever our ROM token is, and changing the JPEG’s included in CapPackage.zip.pdb.

Rebuilding of CapPackage.zip.pdb will be awkward though as the JPEG images will need to be split into record sized (4k) chunks and padded accordingly with the original. So instead, we ensure the filenames contained in CapPackage.zip.pdb don’t match what the XML will look for, by doing that, Varnishator is somewhat defeated and we fall back on the Telephony_UI prc which is much easier to edit with custom splash screens using the same process as for the 650.

We thereby go from custom ROMs with branding like the original Cingular and the rebranded AT&T splashscreens, both unsuitable for an unbranded ROM, to the Treo650 splashscreen (because it was the only stock image I could find). All without having to muck about with copying splashscreen files to RAM which I think is a rather unclean approach until such point as a ROM update arrives for the unlocked GSM 680’s.
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