Re: [Patch] sysinfo compatibility

[Erik Andersen <andersen@codepoet.org>]

On Tue Aug 21, 2001 at 07:30:04PM +0200, Christoph Rohland wrote:
> And I have somewhat harder feelings since we get a lot of bug reports
> that our installer only detects 0M RAM when running on a 2.4 machine
> while it works with the 2.2 kernel. We are talking about an ABI which
> is directly imported into user space programs.

Its your lucky day.  Put something like this in your installer,
and your problems will go away:

/* Include our own copy of struct sysinfo to avoid binary compatibility
 * problems with Linux 2.4, which changed things.  Grumble, grumble. */
struct sysinfo {
    long uptime;            /* Seconds since boot */
    unsigned long loads[3];     /* 1, 5, and 15 minute load averages */
    unsigned long totalram;     /* Total usable main memory size */
    unsigned long freeram;      /* Available memory size */
    unsigned long sharedram;    /* Amount of shared memory */
    unsigned long bufferram;    /* Memory used by buffers */
    unsigned long totalswap;    /* Total swap space size */
    unsigned long freeswap;     /* swap space still available */
    unsigned short procs;       /* Number of current processes */
    unsigned short pad;         /* Padding needed for m68k */
    unsigned long totalhigh;    /* Total high memory size */
    unsigned long freehigh;     /* Available high memory size */
    unsigned int mem_unit;      /* Memory unit size in bytes */
    char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
};
extern int sysinfo (struct sysinfo* info);


/* How much memory does this machine have?
   Units are kBytes to avoid overflow on 4GB machines */
static int check_free_memory()
{
    struct sysinfo info;
    unsigned int result, u, s=10;

    if (sysinfo(&info) != 0) {
        fprintf(stderr,"Error checking free memory");
        return -1;
    }

    /* Kernels 2.0.x and 2.2.x return info.mem_unit==0 with values in bytes.
     * Kernels 2.4.0 return info.mem_unit in bytes. */
    u = info.mem_unit;
    if (u==0) u=1;
    while ( (u&1) == 0 && s > 0 ) { u>>=1; s--; }
    result = (info.totalram>>s) + (info.totalswap>>s);
    result = result*u;
    if (result < 0) result = INT_MAX;
    return result;
}

 -Erik

--
Erik B. Andersen   email:  andersee@debian.org, andersen@lineo.com
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