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SubjectRe: intermittant petabyte usage reported with broadcom nic
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On Sat, 2007-04-14 at 17:20 -0700, Michael Chan wrote:

> I also like Andi's idea of using change_page_attr() to isolate the
> problem. I'll try to send you a debug patch in the next few days to try
> that out. Thanks.
>
Here's the debug patch for x86 only that will change the statistics
memory block to read-only. If the kernel is corrupting it, you should
get a page fault that will crash the system. If you continue to see
bogus counters, it is definitely a firmware or hardware problem. Please
try it and let me know. Thanks.

diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index 0b7aded..b7d491b 100644
--- a/drivers/net/bnx2.c
+++ b/drivers/net/bnx2.c
@@ -47,6 +47,7 @@
#include <linux/prefetch.h>
#include <linux/cache.h>
#include <linux/zlib.h>
+#include <asm/cacheflush.h>

#include "bnx2.h"
#include "bnx2_fw.h"
@@ -436,6 +437,8 @@ bnx2_free_mem(struct bnx2 *bp)
}
}
if (bp->status_blk) {
+ change_page_attr(virt_to_page(bp->status_blk), 1, PAGE_KERNEL);
+ global_flush_tlb();
pci_free_consistent(bp->pdev, bp->status_stats_size,
bp->status_blk, bp->status_blk_mapping);
bp->status_blk = NULL;
@@ -501,6 +504,7 @@ bnx2_alloc_mem(struct bnx2 *bp)
bp->status_stats_size = status_blk_size +
sizeof(struct statistics_block);

+ bp->status_stats_size = PAGE_SIZE;
bp->status_blk = pci_alloc_consistent(bp->pdev, bp->status_stats_size,
&bp->status_blk_mapping);
if (bp->status_blk == NULL)
@@ -508,6 +512,10 @@ bnx2_alloc_mem(struct bnx2 *bp)

memset(bp->status_blk, 0, bp->status_stats_size);

+ /* x86 debug code to see if the kernel is corrupting the statistics */
+ change_page_attr(virt_to_page(bp->status_blk), 1, PAGE_KERNEL_RO);
+ global_flush_tlb();
+
bp->stats_blk = (void *) ((unsigned long) bp->status_blk +
status_blk_size);

@@ -4307,7 +4315,9 @@ bnx2_timer(unsigned long data)
msg = (u32) ++bp->fw_drv_pulse_wr_seq;
REG_WR_IND(bp, bp->shmem_base + BNX2_DRV_PULSE_MB, msg);

+#if 0
bp->stats_blk->stat_FwRxDrop = REG_RD_IND(bp, BNX2_FW_RX_DROP_COUNT);
+#endif

if (bp->phy_flags & PHY_SERDES_FLAG) {
if (CHIP_NUM(bp) == CHIP_NUM_5706)

-
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