There seems to be some misunderstanding here. The SPI PROM that is connected to the small FPGA is programmed with boot code (VGA boot or Unix Console code). It does not hold the FPGA configuration.
The FPGA configuration EEPROM for the small FPGA is contained in the FPGA itself. This integrated EEPROM can not be accessed from the internals of the FPGA, but must be programmed via the JTAG interface. Therefore it can not be tampered with by broken software, because there is no way to get from PCI to internal EEPROM. On 6/10/06, Peter Brett <[EMAIL PROTECTED]> wrote:
On Saturday 10 June 2006 21:25, Jack Carroll wrote: > On Sat, Jun 10, 2006 at 05:58:48PM +0100, Hamish wrote: > > On Saturday 10 June 2006 16:40, Hamish wrote: > > > > [deleted] > > > > > In addition, should we be doing anything with the WP and HOLD pins of > > > the SPI? They don't seem to be defined as an output for the module like > > > the other SPI input pins... Is hold simply to be tied and WP jumpered? > > > Or something else? > > > > Ah. Found this bit in the RevB schematics... They appear to be tied to > > Vcc? No write protect then? Is there any advantage to connecting WP_ to > > the XP6? (Are there any pins free on the XP6 to tie it to? If the XP6 can > > come up with WP_ low, then we can prevent spurious code from over-writing > > the SPI by accident (Or at least till something calls a write_enable > > function first). > > I haven't looked at the OGD1 schematic or the EEPROM's data sheet. > However, this seems to say that the part has physical write protection, > controlled by a separate pin. (Most SPI EEPROMs don't, which has always > annoyed me.) If it does, may I suggest that the write protect pin be > connected to a header, so a jumper plug can disable it? That way, it can > be manually protected against runaway software. Now that is a _really_ good idea. Is it too late to implement it? Maybe making a single jumper write-protect both PROMs would be a good way to do it... Timothy? Howard? Peter -- Quake II build tools maintainer http://tinyurl.com/fkldd v2sw6YShw7$ln5pr6ck3ma8u6/8Lw3+2m0l7Ci6e4+8t4Eb8Aen5+6g6Pa2Xs5MSr5p4 hackerkey.com _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
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