Red Hat Bugzilla – Bug 60709
IDE-DMA might be a cause for kernel crash.
Last modified: 2008-08-01 12:22:52 EDT
From Bugzilla Helper: User-Agent: Mozilla/4.75 [ja] (WinNT; U) Description of problem: When we enable the ide-dma on IA-64 machine, the kernel may crash because of bad dma implementation in kernel 2.4.9-21. Version-Release number of selected component (if applicable): How reproducible: Sometimes Steps to Reproduce: 1. Put 8GB memory onto your IA-64 machine. 2. boot with ide-dma enabled. 3. mount ide-cdrom, ide-floppy and read any data. Actual Results: Some data are broken, and sometime kernel crashes. Expected Results: Nothing's occured, read any data normally. Additional info: We think this is dma logic missimplementation. If the machine has 4GB memory or lower, this issue never occur. But our machine has 8GB... We suppose this is not only for 2.4.9-21, but also 2.4.9-31. We can avoid this to specify kernel option "ide=nodma", however this can't solve all problems. The quick hack below: --- linux/drivers/block/ll_rw_blk.c.orig Tue Mar 5 07:22:08 2002 +++ linux/drivers/block/ll_rw_blk.c Tue Mar 5 06:34:36 2002 @@ -1464,6 +1464,12 @@ blk_max_low_pfn = max_low_pfn; +#ifdef __ia64__ + if(max_low_pfn * PAGE_SIZE >= 0x100000000UL) + blk_max_low_pfn = (0x100000000UL >> PAGE_SHIFT) - 1; +#endif + + #ifdef CONFIG_AMIGA_Z2RAM z2_init(); #endif
Which IDE controller does your machine have ? There are per-controller maximum dma addresses already, which looks like one is wrong (we did test with 32Gb on our ia64)
We tested ide-dma on HITACHI CF-1, which has IDE Controller similar to Intel Lion. The "lspci" command outputs below: 00:03.0 ISA bridge: Intel Corporation 82372FB PCI to ISA Bridge (rev 01) 00:03.1 IDE interface: Intel Corporation 82372FB PIIX4 IDE (rev 01) (prog-if 80 [Master]) 00:03.2 USB Controller: Intel Corporation 82372FB [PCI-to-USB UHCI] (rev 01) (prog-if 00 [UHCI]) 00:03.3 SMBus: Intel Corporation 82372FB System Management Bus Controller (rev 01) We suppose this is not a IDE Controller issue, but ide-dma driver's. IDE Controller can move data by using 64bit dma. But IDE driver(and others) has many 32bit pointer in itself like below: linux/drivers/ide/ide-dma.c: ide_build_dmatable() while (i) { u32 cur_addr; u32 cur_len; cur_addr = sg_dma_address(sg); cur_len = sg_dma_len(sg); : *table++ = cpu_to_le32(cur_addr); sg_dma_address(sg) is defined unsigned long and dma_addr_t in linux/include/asm-ia64/machvec.h and linux/include/asm-ia64/types.h. And cpu_to_le32 is 32bit data however it should be 64bit. The basic issue may be DMA implementation for each devices. Some devices have 64bit DMA, but others don't. For 32bit DMA, kernel alloc buffer below 4GB limit. kernel-2.4.3-12 doesn't have this issue, because this kernel uses old way Software I/O TLB. The patches below change this method, and they may cause this issue. linux-2.4.9-ia64-fancyswiommu.patch linux-2.4.9-blockhighmem.patch In the file linux/drivers/block/ll_rw_blk.c, the variable max_low_pfn specifies "Max page number of system memory", however it should be "Max page number of memory area that DMAC can reach". So, the condition in somewhere which dicides if the kernel allocates dma buffer below 4GB limit, dma_buffer_address > max_low_pfn * PAGE_SIZE sometime false although the dma_buffer_address is above 4GB. And more, we doubt your ide-dma test on IA64 machine with 32GB memory. We have some Intel Lions, they all can't be switched into ide-dma enabled however specifing kernel parameter or using /proc/ide/hdx/settings:using_dma.
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