Octocontrabass wrote:Ethin wrote:Its like its completely saturating the value when it NOTs it, but that doesn't make any sense.
It makes sense for unimplemented BARs. All 32 bits are wired to 0 if the BAR is unimplemented, so when you NOT it you get the highest possible 32-bit integer.
Ethin wrote:Also, what do I do about card bus bridges?
CardBus bridges implement only BAR0, much like how PCI-to-PCI bridges implement BAR0 and BAR1. The other address-related registers decide which address ranges pass through the bridge to address devices behind the bridge. (Except the register at offset 0x44, but your CardBus bridge driver shouldn't use that one.)
Oh okay, thanks. This is my new code (I threw in some debug calls because I'm getting unimplemented BARs for devices that (should) have them -- I'll explain that below):
Code: Select all
let mut idx = 0;
loop {
if (dev.header_type == 0x00 && idx > 5)
|| (dev.header_type == 0x01 && idx > 1)
|| (dev.header_type == 0x02 && idx > 0)
{
break;
}
if dev.bars[&idx] == 0x00 {
break;
}
let real_idx = match idx {
0 => BAR0,
1 => BAR1,
2 => BAR2,
3 => BAR3,
4 => BAR4,
5 => BAR5,
_ => 0,
};
let oldbar = read_dword(addr, real_idx);
let oldbar2 = if !oldbar.get_bit(0) && oldbar.get_bits(1..=2) == 0x02 {
read_dword(addr, real_idx + 4)
} else {
0
};
debug!(
"Read raw BARs from index {:X} and {:X}: {:X}, {:X}",
real_idx,
real_idx + 4,
oldbar,
oldbar2
);
write_dword(addr, real_idx, u32::MAX);
debug!("Wrote {:X} to index {:X}", u32::MAX, real_idx);
if !oldbar.get_bit(0) && oldbar.get_bits(1..=2) == 0x02 {
write_dword(addr, real_idx + 4, u32::MAX);
debug!(
"BAR is 64 bits, so wrote {:X} to index {:X}",
u32::MAX,
real_idx + 4
);
}
let mut bar = read_dword(addr, real_idx);
debug!("Read {:X} from index {:X}", bar, real_idx);
let bar2 = if !oldbar.get_bit(0) && oldbar.get_bits(1..=2) == 0x02 {
read_dword(addr, real_idx + 4)
} else {
0
};
if bar2 != 0x00 {
debug!(
"BAR is 64 bits, so read {:X} from index {:X}",
bar2,
real_idx + 4
);
}
write_dword(addr, real_idx, oldbar);
debug!("Wrote old BAR value: {:X}, index {:X}", oldbar, real_idx);
if bar2 != 0x00 {
write_dword(addr, real_idx + 4, oldbar2);
debug!(
"Wrote old BAR value: {:X}, index {:X}",
oldbar2,
real_idx + 4
);
}
if bar2 == 0x00 {
let mut bar = if !oldbar.get_bit(0) {
*bar.set_bits(0..4, 0)
} else {
*bar.set_bits(0..2, 0)
};
bar = (!bar) + 1;
info!("BAR {} uses {} bytes", idx, bar);
} else {
let mut bar = (bar2 as u64) << 32 | (bar as u64);
bar.set_bits(0..4, 0);
bar = (!bar) + 1;
info!("BAR {} uses {} bytes", idx, bar);
}
if oldbar.get_bits(1..=2) == 0x02 {
idx += 2;
} else {
idx += 1;
}
}
The unimplemented BAR issue is a bit of a weird one. I'm launching qemu and requesting both an NVMe device and an AHCI device each with their own disk images attached to them. This is so I can work on my AHCI and NVMe drivers in sequence and just keep building on the VM as I get more and more of a functional system in future (since I think I've figured out AHCI finally). The device PCI tree looks something like this, and I'm quite confused (this is what my loop finds, not the actual values):
- Device 0:0:0:0 is a host bridge with no BARs
- Device 0:0:1:0 is a VGA-compatible display controller with 1 BAR
- Device 0:0:2:0 is an ethernet NIC with 4 BARs
- Device 0:0:3:0 is a non-volatile memory controller with 1 BAR
- Device 0:0:4:0 is a SATA controller with no BARs
- Device 0:0:5:0 is an audio device with 1 BAR
- Device 0:0:6:0 is a USB controller with 1 BAR
- Devices 0:0:1D:0, 0:0:1D:1, and 0:0:1D:2 are USB controllers with no BARs
- Device 0:0:1D:7 is yet another USB controller with 1 BAR
- Device 0:0:1F:0 is an ISA bridge with no BARs
- Device 0:0:1F:2 is a SATA controller with no BARs
- Device 0:0:1F:3 is an SMBus with no BARs
I've only removed the VirtIO stuff. But it does appear as though all the BARs are being found -- my loop just skips them for some reason. I could iterate through the BARs by key, but the problem is that I'd like to skip upper halves of 32-bit BARs (my initial BAR scan doesn't do this and just pulls in everything, but I'm hoping to refactor that too).
