Max VRAM由开源ATI radeon支持
我有一台ATI HD6370，在Ubuntu 11.10上运行专用的1G。 以下是dmesg的输出
sourajit@sourajit:/etc/X11$ sudo dmesg | grep drm [ 5.149765] [drm] Initialized drm 1.1.0 20060810 [ 5.606144] [drm] radeon defaulting to kernel modesetting. [ 5.606147] [drm] radeon kernel modesetting enabled. [ 5.606436] [drm] initializing kernel modesetting (CEDAR 0x1002:0x68E4 0x17AA:0x397A). [ 5.606630] [drm] register mmio base: 0xE0600000 [ 5.606631] [drm] register mmio size: 131072 [ 6.475815] [drm] Detected VRAM RAM=1024M, BAR=256M [ 6.475819] [drm] RAM width 64bits DDR [ 6.475890] [drm] radeon: 1024M of VRAM memory ready [ 6.475891] [drm] radeon: 512M of GTT memory ready. 但是，这是安装后lspci的输出。 这意味着什么？ radeon实际使用了多少内存？
01:00.0 VGA compatible controller: ATI Technologies Inc Robson CE [AMD Radeon HD 6300 Series] (prog-if 00 [VGA controller]) Subsystem: Lenovo Device 397a Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- SERR- <PERR- INTx- Latency: 0, Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 42 **Region 0: Memory at c0000000 (64-bit, prefetchable) [size=256M] Region 2: Memory at e0600000 (64-bit, non-prefetchable) [size=128K]** Region 4: I/O ports at 3000 [size=256] Expansion ROM at e0620000 [disabled] [size=128K]
它使用1024M。 256M只是CPU可以直接寻址的限制。 其余的RAM可供GPU使用，CPU无需直接触摸它。