On Tue, Jun 10, 2008 at 12:47:38PM -0400, Warren Togami wrote:
> The attached patch by Peter Jones <[EMAIL PROTECTED]> implements
> intelligent placement of the ramdisk in memory during boot of an
> ELF image created by mkelfimage.
I appreciate this patch!
But can you (or Peter) please describe the algorithm in english?
I don't like a commit message that claims code to be intelligent.. :p
> This patch allows a wrapped Fedora i586 kernel to boot on both KVM
> and Artec Group's Thincan DBE61C (coreboot). It probably needs
> more testing in other circumstances.
Thanks again for the patch. See below for some comments.
> diff -up mkelfImage-2.7/linux-i386/convert_params.c.ramdisk_base
> mkelfImage-2.7/linux-i386/convert_params.c
> --- mkelfImage-2.7/linux-i386/convert_params.c.ramdisk_base 2006-03-27
> 18:44:59.000000000 -0500
> +++ mkelfImage-2.7/linux-i386/convert_params.c 2008-05-21
> 12:55:44.000000000 -0400
> @@ -1301,6 +1301,44 @@ static void query_firmware_values(struct
>
> }
>
> +static void relocate_ramdisk(struct param_info *info)
> +{
> + struct e820entry *e820_map;
> + struct e820entry *highest = 0;
> + unsigned long load_addr;
> + int i;
> +
> + e820_map = info->real_mode->e820_map;
> +#if 0
> + printf("initrd_start = 0x%lx\n", info->real_mode->initrd_start);
> + printf("real_mode->e820_map_nr: %d\n", info->real_mode->e820_map_nr);
> +#endif
I think these debugging messages should either be hooked to some
verbose option or simply removed.
> + for (i = 0; i < info->real_mode->e820_map_nr; i++) {
> + if (e820_map[i].type != E820_RAM)
> + continue;
> +#if 0
> + printf("addr: 0x%lx len: %x\n", e820_map[i].addr,
> e820_map[i].size);
> +#endif
..as should this.
> + if (highest && e820_map[i].addr < highest->addr)
> + continue;
> + if (e820_map[i].size < info->real_mode->initrd_size)
> + continue;
Find the highest free RAM block in the e820 map which is big enough to
hold the initrd..
> + if (e820_map[i].addr + info->real_mode->initrd_size >=
> 0x38000000)
> + continue;
..what is this 3.5MB limit about? Also might this condition be
sensitive to an overflow error?
> + highest = &e820_map[i];
> + }
> +
> + if (highest == 0)
> + return;
> +
> + load_addr = highest->addr + highest->size;
> + load_addr -= info->real_mode->initrd_size;
> + load_addr &= ~0xfffUL;
Load the initrd to the top of this RAM block on a 4k boundary.
> +
> + memcpy((void *)load_addr, (void *)info->real_mode->initrd_start,
> info->real_mode->initrd_size);
> + printf("relocating ramdisk to 0x%lx\n", load_addr);
> + info->real_mode->initrd_start = load_addr;
> +}
> /*
> * Debug
> *
> =============================================================================
> @@ -1533,6 +1571,10 @@ void *convert_params(unsigned type, void
> query_firmware_class(&info);
> query_firmware_values(&info);
> query_bootloader_values(&info);
> + if (info.real_mode->initrd_size) {
> + /* Make sure the initrd is in a relatively safe place. */
> + relocate_ramdisk(&info);
> + }
>
> /* Do the hardware setup that linux might forget... */
> hardware_setup(&info);
> diff -up mkelfImage-2.7/linux-i386/mkelf-linux-i386.c.ramdisk_base
> mkelfImage-2.7/linux-i386/mkelf-linux-i386.c
> --- mkelfImage-2.7/linux-i386/mkelf-linux-i386.c.ramdisk_base 2006-03-17
> 09:08:22.000000000 -0500
> +++ mkelfImage-2.7/linux-i386/mkelf-linux-i386.c 2008-05-21
> 10:47:42.000000000 -0400
> @@ -352,6 +352,9 @@ int linux_i386_mkelf(int argc, char **ar
> */
> params->initrd_start = params->initrd_size = 0;
> if (ramdisk_size) {
> + while (ramdisk_base <= kernel_size)
> + ramdisk_base <<= 1;
> +
Does this start with 1MB, then try 2MB, 4MB and so on?
> phdr[index].p_paddr = ramdisk_base;
> phdr[index].p_vaddr = ramdisk_base;
> phdr[index].p_filesz = ramdisk_size;
Please keep in mind to also include Signed-off-by: lines from all who
have touched the patch. Please see
http://www.coreboot.org/Development_Guidelines#Sign-off_Procedure
Thanks again for your contribution!
//Peter
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