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    SubjectRe: [patch 1/7] Extended crashkernel command line
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    * Tue, 25 Sep 2007 20:22:58 +0200
    >
    > This is the generic part of the patch. It adds a parse_crashkernel() function
    > in kernel/kexec.c that is called by the architecture specific code that
    > actually reserves the memory. That function takes the whole command line and
    > looks itself for "crashkernel=" in it.
    []
    > +++ b/include/linux/kexec.h
    > @@ -187,6 +187,8 @@ extern u32 vmcoreinfo_note[VMCOREINFO_NO
    > extern size_t vmcoreinfo_size;
    > extern size_t vmcoreinfo_max_size;
    >
    > +int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
    > + unsigned long long *crash_size, unsigned long long *crash_base);

    I still want to point out my consernes about `unsigned long long long'
    bloat.

    > #else /* !CONFIG_KEXEC */
    > struct pt_regs;
    > --- a/kernel/kexec.c
    > +++ b/kernel/kexec.c
    []
    > +/*
    > + * This function parses command lines in the format
    > + *
    > + * crashkernel=<ramsize-range>:<size>[,...][@<base>]

    #v+
    olecom@flower:/tmp$ grep '@offset' <extended-crashkernel-cmdline.mbox
    crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
    - /* crashkernel=size@offset specifies the size to reserve for a crash
    +While the "crashkernel=size[@offset]" syntax is sufficient for most
    + crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
    + crashkernel=range1:size1[,range2:size2,...][@offset]
    olecom@flower:/tmp$ grep '@base' <extended-crashkernel-cmdline.mbox
    + * crashkernel=size[@base]
    olecom@flower:/tmp$ grep '@<base' <extended-crashkernel-cmdline.mbox
    + * crashkernel=<ramsize-range>:<size>[,...][@<base>]
    olecom@flower:/tmp$ grep '@<offset' <extended-crashkernel-cmdline.mbox
    olecom@flower:/tmp$
    #v-

    > + *
    > + * The function returns 0 on success and -EINVAL on failure.
    > + */
    > +static int __init parse_crashkernel_mem(char *cmdline,
    > + unsigned long long system_ram,
    > + unsigned long long *crash_size,
    > + unsigned long long *crash_base)
    > +{
    > + char *cur = cmdline;
    > +
    > + /* for each entry of the comma-separated list */
    > + do {
    > + unsigned long long start = 0, end = ULLONG_MAX;
    > + unsigned long long size = -1;

    memparse(), as a wrapper for somple_strtoll(), always have a return value
    (zero by default).
    <http://article.gmane.org/gmane.linux.kernel/583426>

    Consider coded error path now, please.

    And why not to make overall result reliable? This is kernel after all.

    I.e. if there's valid `crashkernel=' option, but some parsing errors, why
    not to apply some heuristics with warning in syslog, if user have some
    conf, bootloader (random) errors, but feature still works?

    > +
    > + /* get the start of the range */
    > + start = memparse(cur, &cur);
    > + if (*cur != '-') {
    > + printk(KERN_WARNING "crashkernel: '-' expected\n");
    > + return -EINVAL;
    > + }
    > + cur++;
    > +
    > + /* if no ':' is here, than we read the end */
    > + if (*cur != ':') {
    > + end = memparse(cur, &cur);
    > + if (end <= start) {
    > + printk(KERN_WARNING "crashkernel: end <= start\n");
    > + return -EINVAL;
    > + }
    > + }
    > +
    > + if (*cur != ':') {
    > + printk(KERN_WARNING "crashkernel: ':' expected\n");
    > + return -EINVAL;
    > + }
    > + cur++;
    > +
    > + size = memparse(cur, &cur);
    > + if (size < 0) {
    > + printk(KERN_WARNING "crashkernel: invalid size\n");
    > + return -EINVAL;
    > + }
    > +
    > + /* match ? */
    > + if (system_ram >= start && system_ram <= end) {
    > + *crash_size = size;
    > + break;
    > + }
    > + } while (*cur++ == ',');
    > +
    > + if (*crash_size > 0) {
    > + while (*cur != ' ' && *cur != '@')
    > + cur++;
    > + if (*cur == '@')
    > + *crash_base = memparse(cur+1, &cur);
    > + }
    > +
    > + return 0;
    > +}
    --
    -o--=O`C
    #oo'L O
    <___=E M
    -
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