Expand virtio_block check to other virtual devices
The Android Emulator isn't the only virtual device the virtio-block
detection code is useful for, and those platforms might not set any
discriminating properties to indicate that they are virtual.
Rework the virtio-block major detection to use /proc/devices instead
of hardcoding the assumption that any virtual platform can have
virtio-block at any experimental major; the new code permits only the
exact experimental major assigned to virtio-block.
The new code runs everywhere, but it will only run once and could be
expanded later to detect dynamic or experimental majors.
Bug: 156286088
Change-Id: Ieae805d08fddd0124a397636f04d99194a9ef7e5
diff --git a/model/Disk.cpp b/model/Disk.cpp
index a4324db..4df4e9d 100644
--- a/model/Disk.cpp
+++ b/model/Disk.cpp
@@ -73,8 +73,6 @@
static const unsigned int kMajorBlockScsiO = 134;
static const unsigned int kMajorBlockScsiP = 135;
static const unsigned int kMajorBlockMmc = 179;
-static const unsigned int kMajorBlockExperimentalMin = 240;
-static const unsigned int kMajorBlockExperimentalMax = 254;
static const unsigned int kMajorBlockDynamicMin = 234;
static const unsigned int kMajorBlockDynamicMax = 512;
@@ -88,33 +86,6 @@
kGpt,
};
-static bool isVirtioBlkDevice(unsigned int major) {
- /*
- * The new emulator's "ranchu" virtual board no longer includes a goldfish
- * MMC-based SD card device; instead, it emulates SD cards with virtio-blk,
- * which has been supported by upstream kernel and QEMU for quite a while.
- * Unfortunately, the virtio-blk block device driver does not use a fixed
- * major number, but relies on the kernel to assign one from a specific
- * range of block majors, which are allocated for "LOCAL/EXPERIMENAL USE"
- * per Documentation/devices.txt. This is true even for the latest Linux
- * kernel (4.4; see init() in drivers/block/virtio_blk.c).
- *
- * This makes it difficult for vold to detect a virtio-blk based SD card.
- * The current solution checks two conditions (both must be met):
- *
- * a) If the running environment is the emulator;
- * b) If the major number is an experimental block device major number (for
- * x86/x86_64 3.10 ranchu kernels, virtio-blk always gets major number
- * 253, but it is safer to match the range than just one value).
- *
- * Other conditions could be used, too, e.g. the hardware name should be
- * "ranchu", the device's sysfs path should end with "/block/vd[d-z]", etc.
- * But just having a) and b) is enough for now.
- */
- return IsRunningInEmulator() && major >= kMajorBlockExperimentalMin &&
- major <= kMajorBlockExperimentalMax;
-}
-
static bool isNvmeBlkDevice(unsigned int major, const std::string& sysPath) {
return sysPath.find("nvme") != std::string::npos && major >= kMajorBlockDynamicMin &&
major <= kMajorBlockDynamicMax;
@@ -322,7 +293,7 @@
break;
}
default: {
- if (isVirtioBlkDevice(majorId)) {
+ if (IsVirtioBlkDevice(majorId)) {
LOG(DEBUG) << "Recognized experimental block major ID " << majorId
<< " as virtio-blk (emulator's virtual SD card device)";
mLabel = "Virtual";
@@ -627,7 +598,7 @@
return std::stoi(tmp);
}
default: {
- if (isVirtioBlkDevice(majorId)) {
+ if (IsVirtioBlkDevice(majorId)) {
// drivers/block/virtio_blk.c has "#define PART_BITS 4", so max is
// 2^4 - 1 = 15
return 15;