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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4] xen: Allow a default compiled-in command line using Kconfig
Added 2 new config entries in common/Kconfig:
CMDLINE and CMDLINE_OVERRIDE
Modified the interface common/kernel.c:cmdline_parse().
The 2 new entries allow an embedded command line to be compiled in the
hypervisor.This allows downstreams to set their defaults without modifying
the source code all over the place. Also probably useful for the embedded space.
(See Also: https://xenproject.atlassian.net/browse/XEN-41)
If CMDLINE is set, the cmdline_parse() routine will append the bootloader
command line to this string, forming the complete command line
before parsing. This order of concatenation implies that if any non-cumulative
options are set in both the built-in and bootloader command line,
only the ones in the latter will take effect. And if CMDLINE_OVERRIDE is
set to y, the whole bootloader command line will be ignored, which will be
useful to work around broken bootloaders.
Since some architectures (e.g. x86) allow optional dom0 options to appear after
" -- " in the command line. cmdline_parse() was modified to handle these
dom0 options if the caller request it to do so, and thus architectures
supporting this feature don't need to handle them in their setup.c's anymore.
Signed-off-by: Zhongze Liu <blackskygg@xxxxxxxxx>
---
Changed since v3:
* Remove the CMDLINE_BOOL option.
* Make the option CMDLINE_OVERRIDE depend on EXPERT = "y".
* Move the CMDLINE-related code from various /xen/$(ARCH)/setup.c's to
common/kernel.c:cmdline_parse().
* Dealing with the optional dom0 options in cmdline_parse().
* Remove some pointless initializers.
* Remove unnecessary #ifdef-ary's
---
xen/arch/arm/setup.c | 6 ++---
xen/arch/x86/setup.c | 23 +++++-----------
xen/common/Kconfig | 24 +++++++++++++++++
xen/common/kernel.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++-----
xen/include/xen/lib.h | 2 +-
5 files changed, 103 insertions(+), 26 deletions(-)
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 92a2de6b70..a5ecdbb54a 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -705,7 +705,7 @@ void __init start_xen(unsigned long boot_phys_offset,
size_t fdt_size;
int cpus, i;
paddr_t xen_paddr;
- const char *cmdline;
+ const char *cmdline, *complete_cmdline;
struct bootmodule *xen_bootmodule;
struct domain *dom0;
struct xen_arch_domainconfig config;
@@ -730,8 +730,8 @@ void __init start_xen(unsigned long boot_phys_offset,
fdt_size = boot_fdt_info(device_tree_flattened, fdt_paddr);
cmdline = boot_fdt_cmdline(device_tree_flattened);
- printk("Command line: %s\n", cmdline);
- cmdline_parse(cmdline);
+ complete_cmdline = cmdline_parse(cmdline, NULL, 0);
+ printk("Command line: %s\n", complete_cmdline);
/* Register Xen's load address as a boot module. */
xen_bootmodule = add_boot_module(BOOTMOD_XEN,
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index dab67d5491..dc65d8f389 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -639,7 +639,9 @@ static char * __init cmdline_cook(char *p, const char
*loader_name)
void __init noreturn __start_xen(unsigned long mbi_p)
{
char *memmap_type = NULL;
- char *cmdline, *kextra, *loader;
+ char *cmdline, *loader;
+ const char *complete_cmdline;
+ static char __initdata kextra[MAX_GUEST_CMDLINE];
unsigned int initrdidx, domcr_flags = DOMCRF_s3_integrity;
multiboot_info_t *mbi = __va(mbi_p);
module_t *mod = (module_t *)__va(mbi->mods_addr);
@@ -679,18 +681,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
cmdline = cmdline_cook((mbi->flags & MBI_CMDLINE) ?
__va(mbi->cmdline) : NULL,
loader);
- if ( (kextra = strstr(cmdline, " -- ")) != NULL )
- {
- /*
- * Options after ' -- ' separator belong to dom0.
- * 1. Orphan dom0's options from Xen's command line.
- * 2. Skip all but final leading space from dom0's options.
- */
- *kextra = '\0';
- kextra += 3;
- while ( kextra[1] == ' ' ) kextra++;
- }
- cmdline_parse(cmdline);
+ complete_cmdline = cmdline_parse(cmdline, kextra, sizeof(kextra));
/* Must be after command line argument parsing and before
* allocing any xenheap structures wanted in lower memory. */
@@ -713,7 +704,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
printk("Bootloader: %s\n", loader);
- printk("Command line: %s\n", cmdline);
+ printk("Command line: %s\n", complete_cmdline);
printk("Video information:\n");
@@ -1566,14 +1557,14 @@ void __init noreturn __start_xen(unsigned long mbi_p)
/* Grab the DOM0 command line. */
cmdline = (char *)(mod[0].string ? __va(mod[0].string) : NULL);
- if ( (cmdline != NULL) || (kextra != NULL) )
+ if ( (cmdline != NULL) || strlen(kextra) )
{
static char __initdata dom0_cmdline[MAX_GUEST_CMDLINE];
cmdline = cmdline_cook(cmdline, loader);
safe_strcpy(dom0_cmdline, cmdline);
- if ( kextra != NULL )
+ if ( strlen(kextra) )
/* kextra always includes exactly one leading space. */
safe_strcat(dom0_cmdline, kextra);
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index f2ecbc43d6..d7288abdcc 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -237,4 +237,28 @@ config FAST_SYMBOL_LOOKUP
The only user of this is Live patching.
If unsure, say Y.
+
+config CMDLINE
+ string "Built-in hypervisor command string"
+ default ""
+ ---help---
+ Enter arguments here that should be compiled into the hypervisor
+ image and used at boot time. If the bootloader provides a
+ command line at boot time, it is appended to this string to
+ form the full hypervisor command line, when the system boots.
+ So if the same command line option is not cumulative,
+ and was set both in this string and in the bootloader command line,
+ only the latter (i.e. the one in the bootloader command line),
+ will take effect.
+
+config CMDLINE_OVERRIDE
+ bool "Built-in command line overrides bootloader arguments"
+ default n
+ depends on EXPERT = "y"
+ ---help---
+ Set this option to 'Y' to have the hypervisor ignore the bootloader
+ command line, and use ONLY the built-in command line.
+
+ This is used to work around broken bootloaders. This should
+ be set to 'N' under normal conditions.
endmenu
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 4b87c60845..77544be948 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -22,7 +22,7 @@
enum system_state system_state = SYS_STATE_early_boot;
-xen_commandline_t saved_cmdline;
+xen_commandline_t saved_cmdline = CONFIG_CMDLINE;
static void __init assign_integer_param(
const struct kernel_param *param, uint64_t val)
@@ -46,17 +46,77 @@ static void __init assign_integer_param(
}
}
-void __init cmdline_parse(const char *cmdline)
+/*
+ * Extracts dom0 options from the @cmdline.
+ * Options after ' -- ' separator belong to dom0.
+ * 1. Orphan dom0's options from Xen's command line.
+ * 2. Skip all but final leading space from dom0's options.
+ * 3. Append dom0's options to kextra.
+ */
+static void __init gather_dom0_options(
+ char *cmdline, char *kextra, size_t kextra_len)
+{
+ char *p;
+
+ if ( (p = strstr(cmdline, " -- ")) != NULL )
+ {
+ *p = '\0';
+ p += 3;
+ while ( p[1] == ' ' )
+ p++;
+
+ strlcat(kextra, p, kextra_len);
+ }
+}
+
+/**
+ * cmdline_parse - parses the command line options.
+ *
+ * @cmdline: the command line to be parsed.
+ * @kextra: if not NULL, this will be filled with the optional dom0
options.
+ * (some architecture allows dom0 options to appear after " -- "
in
+ * the cmdline); if set to NULL, the function won't seek for dom0
+ * options.
+ * @kextra_len: length of @kextra, ignored if @kextra is NULL.
+ *
+ * If CONFIG_CMDLINE is set, @cmdline will be appended to CONFIG_CMDLINE
+ * to form the complete cmdline before parsing, and the optional dom0 options
+ * will also be concatenated in the same order before we put them in @kextra.
+ * But if CONFIG_CMDLINE_OVERRIDE is set to y, the whole bootloader command
+ * line will be ignored.
+ * The fucntion retruns the complete command line with the optional dom0
+ * options stripped out.
+ */
+const char* __init cmdline_parse(
+ const char *cmdline, char *kextra, size_t kextra_len)
{
char opt[100], *optval, *optkey, *q;
- const char *p = cmdline;
+ const char *p = saved_cmdline;
const struct kernel_param *param;
int bool_assert;
- if ( cmdline == NULL )
- return;
+ if ( kextra != NULL )
+ kextra[0] = '\0';
- safe_strcpy(saved_cmdline, cmdline);
+ if ( strlen(saved_cmdline) )
+ {
+ if ( kextra != NULL )
+ gather_dom0_options(saved_cmdline, kextra, kextra_len);
+ safe_strcat(saved_cmdline, " ");
+ }
+
+#ifndef CONFIG_CMDLINE_OVERRIDE
+ if ( cmdline != NULL )
+ {
+ safe_strcat(saved_cmdline, cmdline);
+ if ( kextra != NULL )
+ gather_dom0_options(saved_cmdline, kextra, kextra_len);
+ }
+#endif
+
+ if ( !strlen(saved_cmdline) )
+ /* Nothing to parse. */
+ return saved_cmdline;
for ( ; ; )
{
@@ -145,6 +205,8 @@ void __init cmdline_parse(const char *cmdline)
}
}
}
+
+ return saved_cmdline;
}
int __init parse_bool(const char *s)
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 995a85a7db..33e5fbfe20 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -70,7 +70,7 @@
struct domain;
-void cmdline_parse(const char *cmdline);
+const char *cmdline_parse(const char *cmdline, char *kextra, size_t
kextra_len);
int parse_bool(const char *s);
/*#define DEBUG_TRACE_DUMP*/
--
2.12.0
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