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soc:2008:stefanha:journal:week4 [2008/06/21 00:16] stefanha |
soc:2008:stefanha:journal:week4 [2008/06/23 04:58] (current) stefanha |
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| This is false. The Linux driver does offset the DMA address by 30 bytes, but it also offsets the IO buffer by 30 bytes. In the end, it makes no difference and all that has happened is that 30 bytes of the IO buffer have been wasted. The header structure gets written //to// the DMA address, not before it. | This is false. The Linux driver does offset the DMA address by 30 bytes, but it also offsets the IO buffer by 30 bytes. In the end, it makes no difference and all that has happened is that 30 bytes of the IO buffer have been wasted. The header structure gets written //to// the DMA address, not before it. | ||
| + | The next steps for the b44 driver are cleaning it up, making it robust, and testing. Most of the initialization code is straight from the Linux driver. I want to get to grips with it and then simplify it for gPXE. | ||
| + | I have omitted performance optimizations from the Linux driver. The Linux driver has a "copy threshold" which dictates whether to copy a received packet to a fresh IO buf to hand off to the network stack, or whether to remove the current IO buf from the RX ring and pass it straight to the network stack (and allocating a fresh IO buf for the RX ring). I'll talk to Balaji about performance measurement since he's been optimizing his USB driver. | ||
| - | Next steps: | + | **Lilo bzImage debugging still underway**. I made a little bit of progress tonight by determining that the triple-fault happens in the call to ''install''. I think that EIP goes crazy somewhere inside ''install'' and hence the triple fault. I'm sure the issue triggers inside ''install'' since I've placed infinite loops before and after the call. The loop after the call never happens. |
| - | * [b44] Implement TX error handling. | + | |
| - | * [bzImage] Debug Lilo triple-fault. | + | My current debugging cycle is by booting up Damn Small Linux in QEMU and copying over my latest ''gpxe.lkrn'', running ''lilo'', and rebooting into gPXE. This is slow and frustrating. I need to script it but my DSL install seems to be read-only. |
| - | * [GDB] Update [[:dev:gdbstub|GDB stub page]] and screencast when UDP code is merged into mainline. See [[http://grub.enbug.org/DebuggingWithGDB|GRUB GDB wiki page]] for inspiration. | + | |
| - | * [GDB] Real-mode remote debugging. | + | ===== Next week ===== |
| + | On to [[.:week5|Week 5]]. | ||
