Romit, > -----Original Message----- > From: linux-omap-owner@xxxxxxxxxxxxxxx > [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Dasgupta, Romit > Sent: Monday, July 06, 2009 5:00 PM > To: V, Hemanth; linux-arm-kernel@xxxxxxxxxxxxxxxxxxxxxx; > linux-omap@xxxxxxxxxxxxxxx > Subject: RE: User/kernel memory split > > Hemanth, > I might be missing something but please see below: > > > > > >Hemanth, > > Why do you want the split? Do you have > physical mem > 1G > >in your system? > > > >We want to fit 512MB RAM on 2.6.27 Kernel which doesnot have > highmem option. > >We also donot want to disturb the current I/O memory map > > [Romit] As long as your physical memory is slightly less than > 1GB, I do not think highmem is necessary. > For I/O map: Kernel virtual addresses start from 0xC0000000. > Adding 512M to it gives 0xE0000000. So the virtual memory for > IO space needs to be after this. > > Currently the IO Map is > #define L4_WK_34XX_PHYS L4_WK_34XX_BASE /* 0x48300000 */ > #define L4_WK_34XX_VIRT 0xd8300000 > #define L4_WK_34XX_SIZE SZ_1M > > #define L4_PER_34XX_VIRT 0xd9000000 > #define L4_PER_34XX_SIZE SZ_1M > #define L4_EMU_34XX_VIRT 0xe4000000 > #define L4_EMU_34XX_SIZE SZ_64M > > #define OMAP34XX_GPMC_PHYS OMAP34XX_GPMC_BASE /* 0x6E000000 */ > #define OMAP34XX_GPMC_VIRT 0xFE000000 > #define OMAP34XX_GPMC_SIZE SZ_1M > > #define OMAP343X_SMS_VIRT 0xFC000000 > #define OMAP343X_SMS_SIZE SZ_1M > > #define OMAP343X_SDRC_PHYS OMAP343X_SDRC_BASE /* 0x6D000000 */ > #define OMAP343X_SDRC_VIRT 0xFD000000 > #define OMAP343X_SDRC_SIZE SZ_1M > > This is a problem as the existing virtual memory maps for I/O > space would overlap with 512M SDRAM. So, we need to redefine > the virtual mapping after 0xe0000000. The IO_OFFSET is > 0x90000000 currently. > > For L4_WK_34XX_VIRT we need a minimum of 0xe0000000 - > 0x48300000 i.e. 0x97D00000 as the new IO_OFFSET. But using > this new IO_OFFSET for mapping OMAP343x_GPMC_VIRT would > result in an overflow(0x6E000000 + 0x97D00000 = 0x105D00000). > > Using ioremap for these regions might help. But this needs > changes to most drivers. In that case these static mappings > could go away and I think they should. Some ARM kernel expert > may comment! These points were discussed in below thread. http://lists.arm.linux.org.uk/lurker/message/20090626.181403.55450a9c.en.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
