[Qemu-devel] qemu -boot d -cdrom /dev/cd0 on FreeBSD is not good

[Norikatsu Shigemura]

        I tried to install Windows XP SP2 on qemu over FreeBSD 6-current
        like following command, but failed.

        # qemu -boot d -cdrom /dev/cd0 windows.img

        Because find_image_format on qemu/block.c is failed.  This
        problem can be confirmed like following program.
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#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
int main(void)
{
        char buf[2048];
        int fd = open("/dev/cd0", O_RDONLY);
        if(  read(fd, buf, sizeof(buf)) < 0  )  {       /* no problem */
                perror("[1] read error.");
        }
        if(  read(fd, buf, sizeof(buf) / 2) < 0  )  {   /* problem */
                perror("[2] read error.");
        }
}
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        Adhoc-ly, I changed "buf" size to 2048. and confirmed this
        problem was fixed.
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static BlockDriver *find_image_format(const char *filename)
{
    int fd, ret, score, score_max;
    BlockDriver *drv1, *drv;
    uint8_t buf[1024];                                  => buf[2048]
(snip)
    ret = read(fd, buf, sizeof(buf));
    if (ret < 0) {
        close(fd);
        return NULL;
    }
(snip)
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Obtained from:  qemu-0.6.1

        I think magic number 2048 is sector size, but I don't know
        how to get valid read size.  Anyone, do you have any idea?