Re: debug prints

[Hollis Blanchard]

On Jan 23, 2005, at 12:10 PM, Hollis Blanchard wrote:
> Then grub_debug can be set at runtime to enable debugging messages, 
> which could be quite helpful. If we wanted to get fancy, we could turn 
> grub_debug into a set of flags (e.g. FILESYSTEM, PARTITION, DISK, 
> LINUX, MEMORY) to selectively debug specific systems.

Lots of good ideas. It sounds like the code should look like this:

enum grub_debug_area_t {
        GRUB_DEBUG_FILESYSTEM = 0x1,
        GRUB_DEBUG_PARTITION = 0x2,
        GRUB_DEBUG_DISK = 0x4,
        GRUB_DEBUG_LINUX = 0x8,
        GRUB_DEBUG_MEMORY = 0x10,
        ...
};

#ifndef DEBUG
/* the compiler will optimize this function away */
grub_debug_printf (enum grub_debug_area_t area __unused__,
                const char *location __unused__,
                const char *fmt __unused__,
                ...)
{
}
#else
grub_debug_printf (enum grub_debug_area_t area, const char *location, 
const char *fmt, ...)
{
        char *envflags = grub_env_get("debug");
        grub_uint32_t flags = strtoul(envflags);
        va_list ap;
        int ret;

        if (! (flags & area))
                return;

        va_start (ap, fmt);
        ret = grub_vprintf (fmt, ap);
        va_end (ap);
        return ret;
}
#endif

"area" it the bit specifying the type of debug message
"location" a string such as the module name (e.g. "ext2") or even file 
name if desired
"fmt ..." the printf debug string

(To enable all debug messages, you can "set debug -1".)

-Hollis