RE: [Fastboot] [PATCH]IA64 kexec/kdump patch for INIT

Zou, Nanhai
2006-09-07T01:32:38Z

> -----Original Message-----
> From: linux-ia64-owner@vger.kernel.org
> [mailto:linux-ia64-owner@vger.kernel.org] On Behalf Of Takao Indoh
> Sent: 2006Äê9ÔÂ7ÈÕ 9:19
> To: Zou, Nanhai
> Cc: Takao Indoh; Keith Owens; linux-ia64@vger.kernel.org;
> fastboot@lists.osdl.org
> Subject: Re: [Fastboot] [PATCH]IA64 kexec/kdump patch for INIT
>
> On Thu, 7 Sep 2006 08:57:13 +0800, "Zou, Nanhai" wrote:
>
> >> On Wed, 06 Sep 2006 18:06:53 +0900, Takao Indoh wrote:
> >>
> >> >>>+ /* change region of gp to region5 */
> >> >>>+ asm volatile ("movl gp=__gp"::: "memory");
> >> >>
> >> >>Why? gp is already pointing at the kernel code before we enter
> >> >>ia64_init_handler().
> >> >
> >> >The purpose of this code is just changing region of gp from region7 to
> >> >region5. For example, if gp is e000000004ace170, I want to change gp to
> >> ~~~~~~~~~~~~~~~~e000000000ace170
> >> Sorry, I mistook address...
> >>
> >>
> >> Regards,
> >> Takao Indoh
> >>
> > You don't need to set gp here. Control page does not use GP, and
> >purgatory code will set GP to a physical address which was pre-calculated
> >at the time of crash kernel loading.
>
> If gp points region7, panic occurs at kdump_disable_iosapic.
>
> kdump_disable_iosapic(void)
> {
> u32 low32;
> struct iosapic_intr_info *info;
> struct iosapic_rte_info *rte;
> for (info = iosapic_intr_info; info <
> iosapic_intr_info + IA64_NUM_VECTORS; ++info) {
> low32 = info->low32 |= IOSAPIC_MASK;
> list_for_each_entry(rte, &info->rtes,
> rte_list) {
> (snip)
>
> The panic occurs at list_for_each_entry. When I found this problem,
> &info->rtes and rte->rte_list pointed same data but they had different
> address.
>
> &info->rtes => 0xe0000000049231e0
> rte->rte_list => 0xa0000001009231e0
>
> info->rtes points region7 because its address is calculated from gp.
> This difference of address caused panic.
>
> Regards,
> Takao Indoh
>

Ok, ia64_setreg should be better.
We should avoid put inline asm code in C file.

Thanks
Zou Nan hai
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