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From: | Dinar Valeev |
Subject: | Re: [Qemu-devel] [PATCH 1/2] hw/ppc/spapr.c Set default boot order |
Date: | Mon, 26 Jan 2015 13:57:11 +0100 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
On 01/26/2015 01:37 PM, Markus Armbruster wrote:
Dinar Valeev <address@hidden> writes:On 01/26/2015 10:11 AM, Markus Armbruster wrote:address@hidden writes:From: Dinar Valeev <address@hidden> In order to use -boot once=X option we need to have default list where restore to on reset.Really? What happens without this patch?qemu segfaults on reset. 0 > reset-all Segmentation faultNext time, include a backtrace, please.
Ok, sorry for that.
Here's what I think happens. Boot order comes from --boot parameter once, order, or else the machine type's .default_boot_order. The latter is null for you. It gets passed via ppc_spapr_init() to spapr_create_fdt_skel(), which sets qemu,boot-device in the FDT to it, but only when it isn't null. If it comes from parameter once, we additionally register a reset handler to switch it to parameter order or else .default_boot_order on reset. If you specify once, but not order, this is null for you. On reset, reset handler restore_boot_order() runs. Unlike spapr_create_fdt_skel(), it doesn't check for null, and crashes in validate_bootdevices(). Correct?
Yesqemu_register_boot_set is implemented in PATCH 2/2. on reset boot_device is restored to NULL
AFICS SLOF handles qemu,boot-device as boot device, if nothing passed then it goes disk, cdrom, network. Which is the same as "cdn" list.For me, a null .default_boot_order means "machine type does not support boot order" (this is how commit c165473 treats it). Arguably, --boot order and once should be rejected then.
If I understand you correctly, your machine type does support boot order. Giving it a non-null .default_boot_order makes sense then. The appropriate value depends on firmware. It could even be "". The null check in spapr_create_fdt_skel() looks superfluous then. Consider dropping it. Makes sense?
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