On Sat, 07 Apr 2012 01:36:44 -0400, Daniel Kahn Gillmor <d...@fifthhorseman.net> wrote: > In particular, i suspect that *after* the bootloader has turned over > control to the kernel (memtest in this case), the PXE-driven NIC is > continuing to DMA received packets into active RAM.
phcoder sent me the patch below to address the PXE DMA issue.
I tested it against the current bzr head.
My testing grub.cfg is just:
----------------------
serial --speed=115200
terminal_input console serial
terminal_output console serial
linux16 (pxe)/memtest86+.bin console=ttyS0,115200n8
boot
----------------------
Using grub bzr head without this patch, i get these RAM "failures" on
the net-booted ThinkCentre M70 within ~15 seconds on roughly every other
boot (i haven't found the right packets to inject to force the DMA to
happen consistently, alas).
Using grub bzr head with the patch, i have been unable to reproduce
a single RAM failures in more than 20 trials.
I think this patch resolves the issue, and should go into the mainline.
Thanks, phcoder!
--dkg
=== modified file 'grub-core/net/drivers/i386/pc/pxe.c'
--- grub-core/net/drivers/i386/pc/pxe.c 2012-02-08 18:26:01 +0000
+++ grub-core/net/drivers/i386/pc/pxe.c 2012-04-11 12:53:17 +0000
@@ -278,9 +278,14 @@
grub_pxe_close (const struct grub_net_card *dev __attribute__ ((unused)))
{
if (pxe_rm_entry)
- grub_pxe_call (GRUB_PXENV_UNDI_CLOSE,
- (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR,
- pxe_rm_entry);
+ {
+ grub_pxe_call (GRUB_PXENV_UNDI_CLOSE,
+ (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR,
+ pxe_rm_entry);
+ grub_pxe_call (GRUB_PXENV_UNDI_SHUTDOWN,
+ (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR,
+ pxe_rm_entry);
+ }
}
static grub_err_t
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