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Kernel: Move kernel above the 3GB virtual address mark

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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.
This commit is contained in:
Andreas Kling 2020-01-17 19:59:20 +01:00
parent cee597a728
commit e362b56b4f
17 changed files with 325 additions and 125 deletions
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24
Kernel/Devices/PATAChannel.cpp
View file

@ -102,6 +102,8 @@ PATAChannel::PATAChannel(ChannelType type, bool force_pio)
m_dma_enabled.resource() = true;
ProcFS::add_sys_bool("ide_dma", m_dma_enabled);
m_prdt_page = MM.allocate_supervisor_physical_page();
initialize(force_pio);
detect_disks();
}
@ -131,7 +133,7 @@ void PATAChannel::initialize(bool force_pio)
// Let's try to set up DMA transfers.
PCI::enable_bus_mastering(m_pci_address);
m_prdt.end_of_table = 0x8000;
prdt().end_of_table = 0x8000;
m_bus_master_base = PCI::get_BAR4(m_pci_address) & 0xfffc;
m_dma_buffer_page = MM.allocate_supervisor_physical_page();
kprintf("PATAChannel: Bus master IDE: I/O @ %x\n", m_bus_master_base);
@ -253,16 +255,16 @@ bool PATAChannel::ata_read_sectors_with_dma(u32 lba, u16 count, u8* outbuf, bool
current->pid(), lba, count, outbuf);
#endif
m_prdt.offset = m_dma_buffer_page->paddr();
m_prdt.size = 512 * count;
prdt().offset = m_dma_buffer_page->paddr();
prdt().size = 512 * count;
ASSERT(m_prdt.size <= PAGE_SIZE);
ASSERT(prdt().size <= PAGE_SIZE);
// Stop bus master
IO::out8(m_bus_master_base, 0);
// Write the PRDT location
IO::out32(m_bus_master_base + 4, (u32)&m_prdt);
IO::out32(m_bus_master_base + 4, m_prdt_page->paddr().get());
// Turn on "Interrupt" and "Error" flag. The error flag should be cleared by hardware.
IO::out8(m_bus_master_base + 2, IO::in8(m_bus_master_base + 2) | 0x6);
@ -310,7 +312,7 @@ bool PATAChannel::ata_read_sectors_with_dma(u32 lba, u16 count, u8* outbuf, bool
if (m_device_error)
return false;
memcpy(outbuf, m_dma_buffer_page->paddr().as_ptr(), 512 * count);
memcpy(outbuf, m_dma_buffer_page->paddr().offset(0xc0000000).as_ptr(), 512 * count);
// I read somewhere that this may trigger a cache flush so let's do it.
IO::out8(m_bus_master_base + 2, IO::in8(m_bus_master_base + 2) | 0x6);
@ -326,18 +328,18 @@ bool PATAChannel::ata_write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf
current->pid(), lba, count, inbuf);
#endif
m_prdt.offset = m_dma_buffer_page->paddr();
m_prdt.size = 512 * count;
prdt().offset = m_dma_buffer_page->paddr();
prdt().size = 512 * count;
memcpy(m_dma_buffer_page->paddr().as_ptr(), inbuf, 512 * count);
memcpy(m_dma_buffer_page->paddr().offset(0xc0000000).as_ptr(), inbuf, 512 * count);
ASSERT(m_prdt.size <= PAGE_SIZE);
ASSERT(prdt().size <= PAGE_SIZE);
// Stop bus master
IO::out8(m_bus_master_base, 0);
// Write the PRDT location
IO::out32(m_bus_master_base + 4, (u32)&m_prdt);
IO::out32(m_bus_master_base + 4, m_prdt_page->paddr().get());
// Turn on "Interrupt" and "Error" flag. The error flag should be cleared by hardware.
IO::out8(m_bus_master_base + 2, IO::in8(m_bus_master_base + 2) | 0x6);