Imbus/xv6-riscv-kernel
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This commit is contained in:
rsc 2007-08-24 20:28:08 +00:00
parent ffa58d3616
commit 97ac612fb1
5 changed files with 51 additions and 52 deletions
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51
bootmain.c
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@ -31,31 +31,35 @@
#include "x86.h"
#define SECTSIZE 512
#define ELFHDR ((struct elfhdr*) 0x10000) // scratch space
void readseg(uint, uint, uint);
void
cmain(void)
{
struct elfhdr *elf;
struct proghdr *ph, *eph;
void (*entry)(void);
// read 1st page off disk
readseg((uint) ELFHDR, SECTSIZE*8, 0);
elf = (struct elfhdr*)0x10000; // scratch space
// is this a valid ELF?
if(ELFHDR->magic != ELF_MAGIC)
// Read 1st page off disk
readseg((uint)elf, SECTSIZE*8, 0);
// Is this an ELF executable?
if(elf->magic != ELF_MAGIC)
goto bad;
// load each program segment (ignores ph flags)
ph = (struct proghdr*) ((uchar*) ELFHDR + ELFHDR->phoff);
eph = ph + ELFHDR->phnum;
// Load each program segment (ignores ph flags).
ph = (struct proghdr*)((uchar*)elf + elf->phoff);
eph = ph + elf->phnum;
for(; ph < eph; ph++)
readseg(ph->va, ph->memsz, ph->offset);
// call the entry point from the ELF header
// note: does not return!
((void(*)(void)) (ELFHDR->entry & 0xFFFFFF))();
// Call the entry point from the ELF header.
// Does not return!
entry = (void(*)(void))(elf->entry & 0xFFFFFF);
entry();
bad:
outw(0x8A00, 0x8A00);
@ -67,7 +71,7 @@ bad:
void
waitdisk(void)
{
// wait for disk reaady
// Wait for disk ready.
while((inb(0x1F7) & 0xC0) != 0x40)
;
}
@ -76,9 +80,8 @@ waitdisk(void)
void
readsect(void *dst, uint offset)
{
// wait for disk to be ready
// Issue command.
waitdisk();
outb(0x1F2, 1); // count = 1
outb(0x1F3, offset);
outb(0x1F4, offset >> 8);
@ -86,10 +89,8 @@ readsect(void *dst, uint offset)
outb(0x1F6, (offset >> 24) | 0xE0);
outb(0x1F7, 0x20); // cmd 0x20 - read sectors
// wait for disk to be ready
// Read data.
waitdisk();
// read a sector
insl(0x1F0, dst, SECTSIZE/4);
}
@ -98,24 +99,20 @@ readsect(void *dst, uint offset)
void
readseg(uint va, uint count, uint offset)
{
uint end_va;
uint eva;
va &= 0xFFFFFF;
end_va = va + count;
eva = va + count;
// round down to sector boundary
// Round down to sector boundary.
va &= ~(SECTSIZE - 1);
// translate from bytes to sectors, and kernel starts at sector 1
// Translate from bytes to sectors; kernel starts at sector 1.
offset = (offset / SECTSIZE) + 1;
// If this is too slow, we could read lots of sectors at a time.
// We'd write more to memory than asked, but it doesn't matter --
// we load in increasing order.
while(va < end_va) {
readsect((uchar*) va, offset);
va += SECTSIZE;
offset++;
}
for(; va < eva; va += SECTSIZE, offset++)
readsect((uchar*)va, offset);
}