On 11/25/07, Benjamin Herrenschmidt <[EMAIL PROTECTED]> wrote: > > On Sun, 2007-11-25 at 08:30 -0500, Jon Smirl wrote: > > > > > The two cards with x86 firmware return 0xFF for those two readb() > > > instructions, while the X1900 with OF returns 0x00 for the readb(). > > > > > > Could one of the more knowledgeable folk for PPC intricacies suggest > > why > > > those readb calls are returning the wrong data? > > > > I don't know PPC at this low of level but it may be a problem with non > > word-aligned access to memory. I thought readb() was supposed to work > > on all archs and alignment issues are handled inside readb(). Also, > > the readw() may have an endian bug. > > Ugh ? Read be reads -bytes- ! Can you tell me how the hell can a byte > access be non-aligned ?
readb() doesn't work on the dev board I'm currently working with because the flash is wired in such a way that it only works for 16b reads. Maybe calling that an alignment issue is the wrong term. > > BenH, has source code for an x86 emulator that will run on PPC. That > > will let you run the ROMs. The original plan was for the kernel to > > generate a uevent that would have triggered the x86 emulator to run. > > > > Progress along that path was blocked by the X developers. The X server > > contains code for enabling the PCI ROM and reading it from user space. > > I wanted to move this code out of X and into the kernel. > > > > Because the path was blocked things like the PCI ROM API were never > > throughly tested. It works most of the time but the occasional problem > > is still turning up. Once we identify the PPC problem we can fix it in > > the kernel. > > Nobody blocked anything, you are free to develop an emulator triggered > by a uevent, nobody prevented you from doing so. They blocked the X server changes, which rendered the kernel support pointless. But that's all old news. > Now, regarding that user problem, this it totally unrelated as it's a > "mac" card. > > It's possible that it's one of these radeons that disable ROM access via > a register in which case a quirk is needed to re-enable it. -- Jon Smirl [EMAIL PROTECTED] _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
