On Sat, Apr 30, 2016 at 08:57:34AM +0530, Pratyush Anand wrote: > On Fri, Apr 29, 2016 at 11:30 PM, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxxx> wrote: > > On Fri, Apr 29, 2016 at 08:26:00PM +0530, Pratyush Anand wrote: > >> Hi Russell, > >> > >> On Thu, Apr 28, 2016 at 2:58 PM, Russell King > >> <rmk+kernel@xxxxxxxxxxxxxxxx> wrote: > >> > Advertise the location of bootable RAM to kexec-tools. kexec needs to > >> > know where it can place the kernel in RAM, and so be executable when > >> > the system needs to jump into it. > >> > > >> > Advertise these areas in /proc/iomem with a "System RAM (boot alias)" > >> > tag. > >> > > >> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > >> > >> Can you please also share git tree path of corresponding kexec-tools changes? > >> > >> Could it be a better idea (if things in user space become simpler) > >> that in stead of patch 5 and 6, we pass arch_phys_to_idmap_offset to > >> user space, and then user space manipulates existing "Crash kernel" > >> and "System RAM" resources. > > > > Given that it's only _one_ platform right now, I don't think that > > additional complexity is worth it. It means that we have to invent > > Probably, I could not communicate it well. I was not trying to have > *additional* complexity. Wanted to see if things could be simpler > rather. So this is what my understanding was: > -- We create one patch to pass arch_phys_to_idmap_offset to user space > (say in /sys/kernel/bootmem_idmap_offset) > -- We do not use patch 5,6,11 and 12 of this series. Probably few more > content of the series will go away. Patches 11 and 12 don't go away with what you're suggesting. Patches 11 and 12 are necessary to allow the boot-view addresses to be passed into the kernel through kexec, and to allow kexec to find appropriate memory resources. For example, from patch 11: @@ -48,7 +48,8 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry, - if ((entry < crashk_res.start) || (entry > crashk_res.end)) + if ((entry < phys_to_boot_phys(crashk_res.start)) || + (entry > phys_to_boot_phys(crashk_res.end))) "entry" is limited to a 32-bit physical address as it is unsigned long, and is the boot-view physical address. crashk_res.start is the running-view physical address. Without this change, the rest will always be true on Keystone 2. @@ -229,8 +229,8 @@ int sanity_check_segment_list(struct kimage *image) - if ((mstart < crashk_res.start) || - (mend > crashk_res.end)) + if ((mstart < phys_to_boot_phys(crashk_res.start)) || + (mend > phys_to_boot_phys(crashk_res.end))) Same problem - mstart and mend are both 32-bit quantities. The result is the segment list validation always fails. @@ -354,7 +354,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image, - pfn = page_to_pfn(pages); + pfn = page_to_boot_pfn(pages); The result without this change is that we allocate _all_ system memory looking for a suitable page, never finding one because we never find a page which matches. Without a previous patch, killing many processes and taking the system down. @@ -480,7 +480,7 @@ static int kimage_add_entry(struct kimage *image, kimage_entry_t entry) - *image->entry = virt_to_phys(ind_page) | IND_INDIRECTION; + *image->entry = virt_to_boot_phys(ind_page) | IND_INDIRECTION; The physical address would end up being truncated to 32-bits, but would actually be larger than 4GiB. So, *image->entry would point at the incorrect address, and kexec would fail. @@ -535,13 +535,13 @@ void kimage_terminate(struct kimage *image) #define for_each_kimage_entry(image, ptr, entry) \ for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \ ptr = (entry & IND_INDIRECTION) ? \ - phys_to_virt((entry & PAGE_MASK)) : ptr + 1) + boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1) "entry" is truncated to 32-bit, and so this passes an invalid physical address which is not part of the lowmem mapping to phys_to_virt(). The resulting virtual address is undefined. - page = pfn_to_page(entry >> PAGE_SHIFT); + page = boot_pfn_to_page(entry >> PAGE_SHIFT); Same, except the resulting struct page pointer is undefined. ... and so it goes on. The only patches which get replaced are patches 5 and 6 with a new userspace API. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html