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SubjectRe: [patch 1/7] Extended crashkernel command line
Date
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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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