[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] xen/arm: Prevent Dom0 to be loaded when using dom0less
commit fcb97d1f19ab294df091249399e515117350c228 Author: Luca Fancellu <luca.fancellu@xxxxxxx> AuthorDate: Wed Apr 14 10:14:04 2021 +0100 Commit: Julien Grall <jgrall@xxxxxxxxxx> CommitDate: Thu Apr 15 18:08:57 2021 +0100 xen/arm: Prevent Dom0 to be loaded when using dom0less This patch prevents the dom0 to be loaded skipping its building and going forward to build domUs when the dom0 kernel is not found and at least one domU is present. Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx> Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx> Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx> --- docs/features/dom0less.pandoc | 7 ++++--- xen/arch/arm/setup.c | 42 +++++++++++++++++++++++++++++++++++++++--- 2 files changed, 43 insertions(+), 6 deletions(-) diff --git a/docs/features/dom0less.pandoc b/docs/features/dom0less.pandoc index d798596cdf..c9edb529e1 100644 --- a/docs/features/dom0less.pandoc +++ b/docs/features/dom0less.pandoc @@ -16,9 +16,10 @@ Multiboot specification has been extended to allow for multiple domains to be passed to Xen. See docs/misc/arm/device-tree/booting.txt for more information about the Multiboot specification and how to use it. -Currently, a control domain ("dom0") is still required, but in the -future it will become unnecessary when all domains are created -directly from Xen. Instead of waiting for the control domain to be fully +Currently, a control domain ("dom0") is still required to manage the DomU +domains, but the system can start also without dom0 if the Device Tree +doesn't specify the dom0 kernel and it declares one or more domUs. +Instead of waiting for the control domain (when declared) to be fully booted and the Xen tools to become available, domains created by Xen this way are started right away in parallel. Hence, their boot time is typically much shorter. diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index 70a719cbaf..00aad1c194 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -794,6 +794,38 @@ static void __init setup_mm(void) } #endif +static bool __init is_dom0less_mode(void) +{ + struct bootmodules *mods = &bootinfo.modules; + struct bootmodule *mod; + unsigned int i; + bool dom0found = false; + bool domUfound = false; + + /* Look into the bootmodules */ + for ( i = 0 ; i < mods->nr_mods ; i++ ) + { + mod = &mods->module[i]; + /* Find if dom0 and domU kernels are present */ + if ( mod->kind == BOOTMOD_KERNEL ) + { + if ( mod->domU == false ) + { + dom0found = true; + break; + } + else + domUfound = true; + } + } + + /* + * If there is no dom0 kernel but at least one domU, then we are in + * dom0less mode + */ + return ( !dom0found && domUfound ); +} + size_t __read_mostly dcache_line_bytes; /* C entry point for boot CPU */ @@ -804,7 +836,7 @@ void __init start_xen(unsigned long boot_phys_offset, int cpus, i; const char *cmdline; struct bootmodule *xen_bootmodule; - struct domain *dom0; + struct domain *dom0 = NULL; int rc; dcache_line_bytes = read_dcache_line_bytes(); @@ -959,7 +991,10 @@ void __init start_xen(unsigned long boot_phys_offset, enable_errata_workarounds(); /* Create initial domain 0. */ - dom0 = create_dom0(); + if ( !is_dom0less_mode() ) + dom0 = create_dom0(); + else + printk(XENLOG_INFO "Xen dom0less mode detected\n"); heap_init_late(); @@ -977,7 +1012,8 @@ void __init start_xen(unsigned long boot_phys_offset, if ( acpi_disabled ) create_domUs(); - domain_unpause_by_systemcontroller(dom0); + if ( dom0 ) + domain_unpause_by_systemcontroller(dom0); /* Switch on to the dynamically allocated stack for the idle vcpu * since the static one we're running on is about to be freed. */ -- generated by git-patchbot for /home/xen/git/xen.git#master
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