Kernel: Move kernel above the 3GB virtual address mark

The kernel and its static data structures are no longer identity-mapped
in the bottom 8MB of the address space, but instead move above 3GB.

The first 8MB above 3GB are pseudo-identity-mapped to the bottom 8MB of
the physical address space. But things don't have to stay this way!

Thanks to Jesse who made an earlier attempt at this, it was really easy
to get device drivers working once the page tables were in place! :^)

Fixes #734.

1 files changed, 13 insertions, 6 deletions

diff --git a/Kernel/Net/E1000NetworkAdapter.cpp b/Kernel/Net/E1000NetworkAdapter.cpp
index dd9b268893..1450fbd84b 100644
--- a/Kernel/Net/E1000NetworkAdapter.cpp
+++ b/Kernel/Net/E1000NetworkAdapter.cpp
@@ -234,11 +234,14 @@ void E1000NetworkAdapter::initialize_rx_descriptors()
     m_rx_descriptors = (e1000_rx_desc*)ptr;
     for (int i = 0; i < number_of_rx_descriptors; ++i) {
         auto& descriptor = m_rx_descriptors[i];
-        descriptor.addr = (u64)kmalloc_eternal(8192 + 16);
+        auto addr = (u32)kmalloc_eternal(8192 + 16);
+        if (addr % 16)
+            addr = (addr + 16) - (addr % 16);
+        descriptor.addr = addr - 0xc0000000;
         descriptor.status = 0;
     }
 
-    out32(REG_RXDESCLO, ptr);
+    out32(REG_RXDESCLO, (u32)ptr - 0xc0000000);
     out32(REG_RXDESCHI, 0);
     out32(REG_RXDESCLEN, number_of_rx_descriptors * sizeof(e1000_rx_desc));
     out32(REG_RXDESCHEAD, 0);
@@ -256,11 +259,14 @@ void E1000NetworkAdapter::initialize_tx_descriptors()
     m_tx_descriptors = (e1000_tx_desc*)ptr;
     for (int i = 0; i < number_of_tx_descriptors; ++i) {
         auto& descriptor = m_tx_descriptors[i];
-        descriptor.addr = (u64)kmalloc_eternal(8192 + 16);
+        auto addr = (u32)kmalloc_eternal(8192 + 16);
+        if (addr % 16)
+            addr = (addr + 16) - (addr % 16);
+        descriptor.addr = addr - 0xc0000000;
         descriptor.cmd = 0;
     }
 
-    out32(REG_TXDESCLO, ptr);
+    out32(REG_TXDESCLO, (u32)ptr - 0xc0000000);
     out32(REG_TXDESCHI, 0);
     out32(REG_TXDESCLEN, number_of_tx_descriptors * sizeof(e1000_tx_desc));
     out32(REG_TXDESCHEAD, 0);
@@ -348,7 +354,8 @@ void E1000NetworkAdapter::send_raw(const u8* data, int length)
 #endif
     auto& descriptor = m_tx_descriptors[tx_current];
     ASSERT(length <= 8192);
-    memcpy((void*)descriptor.addr, data, length);
+    auto *vptr = (void*)(descriptor.addr + 0xc0000000);
+    memcpy(vptr, data, length);
     descriptor.length = length;
     descriptor.status = 0;
     descriptor.cmd = CMD_EOP | CMD_IFCS | CMD_RS;
@@ -381,7 +388,7 @@ void E1000NetworkAdapter::receive()
         rx_current = (rx_current + 1) % number_of_rx_descriptors;
         if (!(m_rx_descriptors[rx_current].status & 1))
             break;
-        auto* buffer = (u8*)m_rx_descriptors[rx_current].addr;
+        auto* buffer = (u8*)(m_rx_descriptors[rx_current].addr + 0xc0000000);
         u16 length = m_rx_descriptors[rx_current].length;
 #ifdef E1000_DEBUG
         kprintf("E1000: Received 1 packet @ %p (%u) bytes!\n", buffer, length);