Re: e1000 and PXE issues

[Avi Kivity <avi@qumranet.com>]

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Greg Kurtzer wrote:
> Hello,
>
> I noticed some problems with the e1000 implementation in kvm >= 70. At
> first glance it seemed liked a PXE problem as it would not acknowledge
> the DHCP offer from the server. I tried several different Etherboot
> ROM images and version 5.2.6 seemed to work. That version isn't PXE
> compliant so I built an ELF image to boot, and it downloaded it very,
> very, very, very slowly (as in about 10 minutes) but it did end up
> working.
>
> This all worked perfectly with version 69 and previous.
>   

There are two patches to e1000 in kvm-70; can you try backing them out 
(patch -Rp1 < test.patch) to see which one is guilty?

Candidates attached.


-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


[-- Attachment #2: test1.patch --]
[-- Type: text/x-patch, Size: 1291 bytes --]

commit 2ec717a98c8b8e0c8f1ddc562115ca81d2dc024e
Author: Laurent Vivier <Laurent.Vivier@bull.net>
Date:   Fri May 30 16:07:31 2008 +0200

    kvm: qemu: coalesced MMIO support (e1000)
    
    This patch defines coalesced MMIO zones for e1000 ethernet card.
    
    Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
    Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
index 01f8983..5b3a365 100644
--- a/qemu/hw/e1000.c
+++ b/qemu/hw/e1000.c
@@ -26,6 +26,7 @@
 #include "hw.h"
 #include "pci.h"
 #include "net.h"
+#include "qemu-kvm.h"
 
 #include "e1000_hw.h"
 
@@ -938,6 +939,18 @@ e1000_mmio_map(PCIDevice *pci_dev, int region_num,
 
     d->mmio_base = addr;
     cpu_register_physical_memory(addr, PNPMMIO_SIZE, d->mmio_index);
+
+    if (kvm_enabled()) {
+	int i;
+        uint32_t excluded_regs[] = {
+            E1000_MDIC, E1000_ICR, E1000_ICS, E1000_IMS,
+            E1000_IMC, E1000_TCTL, E1000_TDT, PNPMMIO_SIZE
+        };
+        qemu_kvm_register_coalesced_mmio(addr, excluded_regs[0]);
+        for (i = 0; excluded_regs[i] != PNPMMIO_SIZE; i++)
+            qemu_kvm_register_coalesced_mmio(addr + excluded_regs[i] + 4,
+                             excluded_regs[i + 1] - excluded_regs[i] - 4);
+    }
 }
 
 static int

[-- Attachment #3: test2.patch --]
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commit 404ce95cb202ca6015beb26e9b870f91c0309ee0
Author: Anthony Liguori <aliguori@us.ibm.com>
Date:   Wed May 7 16:40:58 2008 -0500

    kvm: qemu: fix e1000 can_receive handler
    
    The current logic of the can_receive handler is to allow packets whenever the
    receiver is disabled or when there are descriptors available in the ring.
    
    I think the logic ought to be to allow packets whenever the receiver is enabled
    and there are descriptors available in the ring.
    
    Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
    Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
index 0728539..01f8983 100644
--- a/qemu/hw/e1000.c
+++ b/qemu/hw/e1000.c
@@ -520,8 +520,8 @@ e1000_can_receive(void *opaque)
 {
     E1000State *s = opaque;
 
-    return (!(s->mac_reg[RCTL] & E1000_RCTL_EN) ||
-            s->mac_reg[RDH] != s->mac_reg[RDT]);
+    return ((s->mac_reg[RCTL] & E1000_RCTL_EN) &&
+	    s->mac_reg[RDH] != s->mac_reg[RDT]);
 }
 
 static void