20cc673a41
The TCP/IP stack reached straight into the first driver anyone wrote.
net.c called e1000_present(), the lwIP glue was named netif_e1000.c and
called e1000_transmit(), and include/defs.h declared the driver's
internals to the whole kernel. The second NIC driver would therefore
have arrived with a near-identical copy of the glue file and a patch to
the protocol stack, which is the arrangement include/device.h was
written to prevent -- the e1000 even said so, with `.ops = 0, // no
class vtable yet; there is no net class`.
There is now. A driver publishes a struct netdev_ops -- transmit,
receive, mac, link_up -- and is finished: it never mentions lwIP, and
nothing above it learns its name. The display class was already this
shape; this is the same shape for networking, and the two now read the
same way in kernel/dev/device.c.
What that made possible immediately:
- One netif per bound device instead of one per driver. lwIP's glue is
netif_eth.c, it takes a struct device, and it holds up to NETIF_MAX
interfaces. net.c attaches every network device it finds and starts
DHCP on each, because which interface the network answers on is not
ours to decide.
- /proc/netif lists all of them, one block of fields each, with the
interface name and the driver that claimed it.
- The ARP self-test moved from the e1000 to the class. Nothing in it
was chip-specific, and it is the first thing anyone will want to run
against the next driver. Still `echo n > /proc/sysrq`.
- Private headers live with their driver: e1000.h was in include/,
where exactly one file could use it. The driver build now adds the
driver's own directory to the include path.
The e1000 also drives more than one card. Its probe() refused the second
outright, because there was a single static instance -- so a machine
with two of them drove one and silently ignored the other. Instances are
an array now, and the instance is hung on dev->priv by a new optional
`attached` hook that the bus calls once the device exists. probe() runs
before device_add(), so there was previously nowhere to put it; that is
the whole reason the hook exists rather than a line inside probe.
QEMU gets an explicit NIC on every target (QEMU_NET). The default device
happens to be an e1000 on this machine type today, which is exactly the
sort of thing that stays true until a QEMU release changes it and the
network stops being exercised without anyone noticing.
Verified:
- bootcheck -Net passes, 48 [ok], no failures -- including the moved
self-test and two new checks that /proc/netif names both the
interface and the driver behind it, which together say the stack
went through the class rather than through a driver it was compiled
to know.
- Two NICs attached by hand (-device e1000 twice, second with its own
MAC): eth0 and eth1 both attach, each reports its own MAC in
/proc/netif, and each gets its own DHCP lease. Before this commit
the same machine produced one interface.
- make schfs-check still passes in full.
One trap worth recording: moving a header broke the build for anyone
with stale .d files -- make stopped with "No rule to make target
'include/e1000.h'". CFLAGS gains -MP, which emits a phony target per
header so a moved or deleted one can never wedge the build again.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
45 lines
2.2 KiB
C
45 lines
2.2 KiB
C
#pragma once
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#define NPROC 128 // maximum number of processes
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#define KSTACKSIZE 4096 // size of per-process kernel stack (increased for x64)
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#define KSTACK_CANARY 0xDEADC0DEDEADC0DEULL // sentinel at kstack[0], see kstack_check_canary()
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#define NCPU 16 // maximum number of CPUs
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#define NOFILE 128 // open files per process
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#define NFILE 512 // open files per system
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#define NINODE 200 // maximum number of active i-nodes
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#define NDEV 10 // maximum major device number
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#define RAMDISK_DEV 2 // memory-backed block device (kernel/dev/ramdisk.c)
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#define USBDISK_DEV 3 // USB mass storage (kernel/drivers/usb_storage.c)
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// Device the root filesystem is mounted from. Building with RAMROOT=1 defines
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// RAMDISK_ROOT and boots from the SCHFS image linked into the kernel instead
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// of the IDE disk, leaving the physical disk free to be reformatted from a
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// running system. See kernel/dev/ramdisk.c.
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#ifdef RAMDISK_ROOT
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#define ROOTDEV RAMDISK_DEV
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#else
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#define ROOTDEV 1 // device number of file system root disk
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#endif
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#define MAXARG 32 // max exec arguments
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#define MAXPATH 128 // max path
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#define MAXOPBLOCKS 30 // max # of blocks any FS op writes
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#define LOGSIZE (MAXOPBLOCKS*3) // max data blocks in on-disk log
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// Disk block cache, in blocks. 256 * BSIZE = 1 MB.
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//
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// Was MAXOPBLOCKS*3 = 90 blocks, and at the old 1 KB BSIZE that is a 90 KB
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// cache -- smaller than the toybox binary that every single command execs. So
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// nothing was ever still resident on the next command and each one paid the
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// full read again. 1 MB holds toybox with room to spare, which is what makes
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// the *second* command fast rather than just the first.
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//
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// Sized rather than maximised: these are statically allocated in bio.c, so
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// this is memory the system always spends. 1 MB is affordable on a machine
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// with tens of megabytes; 8 MB would not be.
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#define NBUF 256
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#define FSSIZE 150000 // size of file system in blocks
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// Network interfaces the stack will attach. Two is already an ordinary machine
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// -- a laptop with Ethernet plus a virtual adapter -- and each one costs a
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// struct netif, so the limit is about keeping a fixed array honest rather than
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// about memory.
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#define NETIF_MAX 4
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