| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | Some notes for ftape users with PCI motherboards: |
| 2 | ================================================= |
| 3 | |
| 4 | The problem: |
| 5 | ------------ |
| 6 | |
| 7 | There have been some problem reports from people using PCI-bus based |
| 8 | systems getting overrun errors. |
| 9 | I wasn't able to reproduce these until I ran ftape on a Intel Plato |
| 10 | (Premiere PCI II) motherboard with bios version 1.00.08AX1. |
| 11 | It turned out that if GAT (Guaranteed Access Timing) is enabled (?) |
| 12 | ftape gets a lot of overrun errors. |
| 13 | The problem disappears when disabling GAT in the bios. |
| 14 | Note that Intel removed this setting (permanently disabled) from the |
| 15 | 1.00.10AX1 bios ! |
| 16 | |
| 17 | It looks like that if GAT is enabled there are often large periods |
| 18 | (greater than 120 us !??) on the ISA bus that the DMA controller cannot |
| 19 | service the floppy disk controller. |
| 20 | I cannot imagine this being acceptable in a decent PCI implementation. |
| 21 | Maybe this is a `feature' of the chipset. I can only speculate why |
| 22 | Intel choose to remove the option from the latest Bios... |
| 23 | |
| 24 | The lesson of this all is that there may be other motherboard |
| 25 | implementations having the same of similar problems. |
| 26 | If you experience a lot of overrun errors during a backup to tape, |
| 27 | see if there is some setting in the Bios that may influence the |
| 28 | bus timing. |
| 29 | |
| 30 | I judge this a hardware problem and not a limitation of ftape ;-) |
| 31 | My DOS backup software seems to be suffering from the same problems |
| 32 | and even refuses to run at 1 Mbps ! |
| 33 | Ftape will reduce the data-rate from 1 Mbps to 500 Kbps if the number |
| 34 | of overrun errors on a track exceeds a threshold. |
| 35 | |
| 36 | |
| 37 | Possible solutions: |
| 38 | ------------------- |
| 39 | |
| 40 | Some of the problems were solved by upgrading the (flash) bios. |
| 41 | Other suggest that it has to do with the FDC being on the PCI |
| 42 | bus, but that is not the case with the Intel Premiere II boards. |
| 43 | [If upgrading the bios doesn't solve the problem you could try |
| 44 | a floppy disk controller on the isa-bus]. |
| 45 | |
| 46 | Here is a list of systems and recommended BIOS settings: |
| 47 | |
| 48 | |
| 49 | Intel Premiere PCI (Revenge): |
| 50 | |
| 51 | Bios version 1.00.09.AF2 is reported to work. |
| 52 | |
| 53 | |
| 54 | |
| 55 | Intel Premiere PCI II (Plato): |
| 56 | |
| 57 | Bios version 1.00.10.AX1 and version 11 beta are ok. |
| 58 | If using version 1.00.08.AX1, GAT must be disabled ! |
| 59 | |
| 60 | |
| 61 | |
| 62 | ASUS PCI/I-SP3G: |
| 63 | |
| 64 | Preferred settings: ISA-GAT-mode : disabled |
| 65 | DMA-linebuffer-mode : standard |
| 66 | ISA-masterbuffer-mode : standard |
| 67 | |
| 68 | |
| 69 | DELL Dimension XPS P90 |
| 70 | |
| 71 | Bios version A2 is reported to be broken, while bios version A5 works. |
| 72 | You can get a flash bios upgrade from http://www.dell.com |
| 73 | |
| 74 | |
| 75 | To see if you're having the GAT problem, try making a backup |
| 76 | under DOS. If it's very slow and often repositions you're |
| 77 | probably having this problem. |
| 78 | |
| 79 | --//-- |
| 80 | LocalWords: ftape PCI bios GAT ISA DMA chipset Mbps Kbps FDC isa AF ok ASUS |
| 81 | LocalWords: SP linebuffer masterbuffer XPS http www com |