Xen project Mailing List

[PATCH v9 02/20] xen/dom0less: turn max_init_domid into a common variable

From: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

Date: Wed, 9 Sep 2026 17:07:20 +0200

Authentication-results: eu.smtp.expurgate.cloud; dkim=pass header.s=20251104 header.d=gmail.com header.i="@gmail.com" header.h="Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From"

Cc: Romain Caritey <Romain.Caritey@xxxxxxxxxxxxx>, Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>, Zheng Zhang <zhangzheng@xxxxxxxxxxx>, Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger@xxxxxxxxxxxxxx>, Timothy Pearson <tpearson@xxxxxxxxxxxxxxxxxxxxx>, Alistair Francis <alistair.francis@xxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>

Delivery-date: Wed, 09 Sep 2026 15:08:29 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Until now every architecture carried its own notion of max_init_domid: Arm defined a real variable (declared in asm/setup.h, defined in setup.c), while ppc, riscv and x86 each provided a "#define max_init_domid (0)" stub in their asm/setup.h. This duplicated the same declaration across all arches and placed a purely dom0less concept in arch setup headers. Now that the dom0less build code lives in common (xen/common/ device-tree/dom0less-build.c sets max_init_domid, and the console serial-input switcher reads it), there is no reason for the symbol to be per-arch. Provide a single declaration in <xen/dom0less-build.h>, with the !CONFIG_DOM0LESS_BOOT stub kept there as well, so there is one source of truth and the arch headers no longer need to mention it. Update console.c to include <xen/dom0less-build.h> for the declaration instead of relying on asm/setup.h, and drop the now unneeded <asm/setup.h> include. Place the definition in xen/common/domid.c rather than in dom0less- build.c. The latter is built as dom0less-build.init.o, i.e. the whole object is relocated into the .init.* sections and freed after boot, whereas max_init_domid must outlive boot because it is read at runtime by the console serial-input switcher. domid.c is always linked (obj-y) and resides in regular (non-init) sections, so it is a correct home for the variable. It is marked __ro_after_init since it is only updated while creating boot-time domains and read-only afterwards, and guarded by CONFIG_DOM0LESS_BOOT as domid.c itself is unconditional. While at it, make <xen/dom0less-build.h> self-contained: it includes <public/xen.h>, which uses the fixed-width types provided by <xen/types.h>, so include the latter explicitly rather than relying on the includer having pulled it in first. This becomes necessary as soon as <xen/dom0less-build.h> comes first in an alphabetically sorted include list, as it now does in domid.c. Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx> --- Changes in v9: - Sort the includes in domid.c alphabetically ("dom0less" before "domain") and add <xen/types.h> to <xen/dom0less-build.h>, which the re-ordering requires. - Drop the leftover <asm/setup.h> include from console.c as nothing from it depends in console.c anymore. - Add Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>. --- Changes in v6-8: - Nothing changed. Only rebase. --- Changes in v5: - Add Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- Changes in v4: - New patch. --- --- xen/arch/arm/include/asm/setup.h | 2 -- xen/arch/arm/setup.c | 2 -- xen/arch/ppc/include/asm/setup.h | 2 -- xen/arch/riscv/include/asm/setup.h | 2 -- xen/arch/x86/include/asm/setup.h | 2 -- xen/common/domid.c | 5 +++++ xen/drivers/char/console.c | 2 +- xen/include/xen/dom0less-build.h | 8 ++++++++ 8 files changed, 14 insertions(+), 11 deletions(-) diff --git a/xen/arch/arm/include/asm/setup.h b/xen/arch/arm/include/asm/setup.h index 0adfa4993a8f..2af780512540 100644 --- a/xen/arch/arm/include/asm/setup.h +++ b/xen/arch/arm/include/asm/setup.h @@ -25,8 +25,6 @@ struct map_range_data struct rangeset *irq_ranges; }; -extern domid_t max_init_domid; - void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len); size_t estimate_efi_size(unsigned int mem_nr_banks); diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index 6310a47d68b6..86532d0a35b6 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -62,8 +62,6 @@ struct cpuinfo_arm __read_mostly system_cpuinfo; bool __read_mostly acpi_disabled; #endif -domid_t __read_mostly max_init_domid; - static __used void noreturn init_done(void) { /* Must be done past setting system_state. */ diff --git a/xen/arch/ppc/include/asm/setup.h b/xen/arch/ppc/include/asm/setup.h index e4f64879b68c..956fa6985adb 100644 --- a/xen/arch/ppc/include/asm/setup.h +++ b/xen/arch/ppc/include/asm/setup.h @@ -1,6 +1,4 @@ #ifndef __ASM_PPC_SETUP_H__ #define __ASM_PPC_SETUP_H__ -#define max_init_domid (0) - #endif /* __ASM_PPC_SETUP_H__ */ diff --git a/xen/arch/riscv/include/asm/setup.h b/xen/arch/riscv/include/asm/setup.h index 2215894cfbb1..73ce2f293348 100644 --- a/xen/arch/riscv/include/asm/setup.h +++ b/xen/arch/riscv/include/asm/setup.h @@ -5,8 +5,6 @@ #include <xen/types.h> -#define max_init_domid (0) - void setup_mm(void); void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len); diff --git a/xen/arch/x86/include/asm/setup.h b/xen/arch/x86/include/asm/setup.h index b01e83a8ed9f..5925c5f39cff 100644 --- a/xen/arch/x86/include/asm/setup.h +++ b/xen/arch/x86/include/asm/setup.h @@ -68,6 +68,4 @@ extern bool opt_dom0_verbose; extern bool opt_dom0_cpuid_faulting; extern bool opt_dom0_msr_relaxed; -#define max_init_domid (0) - #endif diff --git a/xen/common/domid.c b/xen/common/domid.c index b0258e477c1a..c0cb025609b8 100644 --- a/xen/common/domid.c +++ b/xen/common/domid.c @@ -8,8 +8,13 @@ * Copyright 2025 Ford Motor Company */ +#include <xen/dom0less-build.h> #include <xen/domain.h> +#ifdef CONFIG_DOM0LESS_BOOT +domid_t __ro_after_init max_init_domid; +#endif + static DEFINE_SPINLOCK(domid_lock); static DECLARE_BITMAP(domid_bitmap, DOMID_FIRST_RESERVED); diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c index fcacf37c52f0..e4df0bbc2eec 100644 --- a/xen/drivers/char/console.c +++ b/xen/drivers/char/console.c @@ -30,7 +30,7 @@ #include <xen/early_printk.h> #include <xen/warning.h> #include <xen/pv_console.h> -#include <asm/setup.h> +#include <xen/dom0less-build.h> #include <xen/sections.h> #include <xen/consoled.h> diff --git a/xen/include/xen/dom0less-build.h b/xen/include/xen/dom0less-build.h index 4118dec76c0a..75bfaa185fa6 100644 --- a/xen/include/xen/dom0less-build.h +++ b/xen/include/xen/dom0less-build.h @@ -4,6 +4,9 @@ #define XEN_DOM0LESS_BUILD_H #include <xen/stdbool.h> +#include <xen/types.h> + +#include <public/xen.h> struct domain; @@ -13,6 +16,9 @@ struct boot_domain; struct dt_device_node; struct kernel_info; +/* Highest domain ID assigned to a boot-time (dom0less) domain. */ +extern domid_t max_init_domid; + /* * List of possible features for dom0less domUs * @@ -72,6 +78,8 @@ static inline bool is_dom0less_mode(void) } static inline void set_xs_domain(struct domain *d) {} +#define max_init_domid 0 + #endif /* CONFIG_DOM0LESS_BOOT */ #endif /* __ASM_GENERIC_DOM0LESS_BUILD_H__ */ -- 2.55.0

©2013 Xen Project, A Linux Foundation Collaborative Project. All Rights Reserved.
Linux Foundation is a registered trademark of The Linux Foundation.
Xen Project is a trademark of The Linux Foundation.