6 Sep
2012
6 Sep
'12
6:08 p.m.
From: Meelis Roos mroos@linux.ee Date: Thu, 6 Sep 2012 17:41:13 +0300 (EEST)
And here the machine hangs. Debugging printk-s reveal that it does not find any active I/O port resources and then continues into initializing the card. Down in igp_read_bios_from_vram() it successfully ioremaps memory region 0 (vram_base=1ff08000000 and size=40000) and tries to read 2 bytes from there and hangs on reading bios[0].
Mappings obtained from ioremap() may not be derefenced directly.
What you get back from ioremap() isn't a pointer. It's an opaque __iomem cookie, which must only be used via readl() et al.
On sparc64 ioremap() happens to return a physical address, that's why this non-portable code crashes.