Messages in this thread | | | Subject | Re: [PATCH 5/5] lguest: loading bzImage directly | From | Chris Malley <> | Date | Wed, 03 Oct 2007 10:37:01 +0100 |
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Hi guys
Would it not be clearer to #include <asm/bootparam.h> and use the relevant named members of struct setup_header / struct boot_params rather than the hard-coded values 0x202, 0x1F1, 0x214 ?
-- Chris
On Wed, 2007-10-03 at 09:40 +1000, Rusty Russell wrote: [snip] > + u8 hdr[1024]; > + int r; > + /* Modern bzImages get loaded at 1M. */ > + void *p = from_guest_phys(0x100000); > + > + /* Go back to the start of the file and read the header. It should be > + * a Linux boot header (see Documentation/i386/boot.txt) */ > + lseek(fd, 0, SEEK_SET); > + read(fd, hdr, sizeof(hdr)); > + > + /* At offset 0x202, we expect the magic "HdrS" */ > + if (memcmp(hdr + 0x202, "HdrS", 4) != 0) > + errx(1, "This doesn't look like a bzImage to me"); > + > + /* The byte at 0x1F1 tells us how many extra sectors of > + * header: skip over them all. */ > + lseek(fd, (unsigned long)(hdr[0x1F1]+1) * 512, SEEK_SET); > + > + /* Now read everything into memory. in nice big chunks. */ > + while ((r = read(fd, p, 65536)) > 0) > + p += r; > + > + /* Finally, 0x214 tells us where to start the kernel. */ > + return *(unsigned long *)&hdr[0x214]; > } > > /*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels >
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