add launchpad bug reports without comments

1 files changed, 22 insertions, 0 deletions

diff --git a/results/scraper/launchpad-without-comments/1901359 b/results/scraper/launchpad-without-comments/1901359
new file mode 100644
index 000000000..2b594097c
--- /dev/null
+++ b/results/scraper/launchpad-without-comments/1901359
@@ -0,0 +1,22 @@
+ignore bit 0 in pci CONFIG_ADDRESS register write for Type 1 access
+
+I'v recently stumbled upon a bug in the Plan9 PCI config space access routines for config mode #1.
+
+The code used to set bit 0 in the CONFIG_ADDRESS register for a Type 1 access.
+
+This was most likely a misreading of the PCI local bus specification on our side.
+
+However, in the PCI local bus specification 3.0, it states the following:
+
+> 3.2.2.3.2 Software Generation of Configuration Transactions
+> ...
+> For Type 1 translations, the host bridge directly copies the contents of the
+> CONFIG_ADDRESS register (excluding bits 31 and 0) onto the PCI AD lines during the
+> address phase of a configuration transaction making sure that AD[1::0] is "01".
+
+note the: "excluding bits 31 and 0"
+
+What happens in qemu instead is that it uses bit 0 of the CONFIG_ADDRESS
+register as part of the register offset (when it probably should ignore it)
+when translating from Type 1 to Type 0 address. So once it reaches the device
+behind the bridge the register address is off by one.
\ No newline at end of file