On 10/7/24 14:55, Jason Andryuk wrote:
On 2024-10-06 17:49, Daniel P. Smith wrote:
The purpose of struct boot_module is to encapsulate the state of boot
module as
it is processed by Xen. Locating boot module state struct boot_module
reduces
the number of global variables as well as the number of state
variables that
must be passed around. It also lays the groundwork for hyperlaunch
mult-domain
construction, where multiple instances of state variables like
headroom will be
needed.
Signed-off-by: Daniel P. Smith <dpsm...@apertussolutions.com>
---
xen/arch/x86/include/asm/bootinfo.h | 5 +++++
xen/arch/x86/setup.c | 23 ++++++++++++++---------
2 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/xen/arch/x86/include/asm/bootinfo.h
b/xen/arch/x86/include/asm/bootinfo.h
index d19473d8941e..c7e6b4ebf0da 100644
--- a/xen/arch/x86/include/asm/bootinfo.h
+++ b/xen/arch/x86/include/asm/bootinfo.h
@@ -17,6 +17,11 @@
struct boot_module {
/* Transitionary only */
module_t *mod;
+ /*
+ * A boot module may contain a compressed kernel that Xen will
need space
+ * reserved, into which it will be decompressed.
Maybe "Extra space, before the module data, for compressed kernel
modules to be decompressed into."
I will rework it with your suggestions.
And some ascii art could help:
[ headroom ][ compressed data ]
<decompression>
[ decompressed data ]
(Not sure how to create a down arrow...)
Yes, in fact I would just show the three states like this:
At boot:
[ compressed kernel ]
After boot module relocation:
[ estimated headroom + PAGE_SIZE rounding ][ compressed kernel ]
After kernel decompression:
[ decompressed kernel ][ unused rounding ]
+ */
+ unsigned long headroom;
};
/*
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index ba9f110d98c6..dd82ca3d43e2 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1012,7 +1012,7 @@ void asmlinkage __init noreturn
__start_xen(unsigned long mbi_p)
struct boot_info *bi;
multiboot_info_t *mbi;
module_t *mod;
- unsigned long nr_pages, raw_max_page, modules_headroom,
module_map[1];
+ unsigned long nr_pages, raw_max_page, module_map[1];
int i, j, e820_warn = 0, bytes = 0;
unsigned long eb_start, eb_end;
bool acpi_boot_table_init_done = false, relocated = false;
@@ -1371,7 +1371,10 @@ void asmlinkage __init noreturn
__start_xen(unsigned long mbi_p)
mod[bi->nr_modules].mod_end = __2M_rwdata_end - _stext;
}
- modules_headroom = bzimage_headroom(bootstrap_map(mod),
mod->mod_end);
+ bi->mods[0].headroom =
+ bzimage_headroom(bootstrap_map(bi->mods[0].mod),
+ bi->mods[0].mod->mod_end);
+
bootstrap_map(NULL);
#ifndef highmem_start
@@ -1456,8 +1459,10 @@ void asmlinkage __init noreturn
__start_xen(unsigned long mbi_p)
* decompressor overheads of mod[0] (the dom0 kernel).
When we
* move mod[0], we incorporate this as extra space at
the start.
*/
- unsigned long headroom = j ? 0 : modules_headroom;
- unsigned long size = PAGE_ALIGN(headroom + mod[j].mod_end);
+ struct boot_module *bm = &bi->mods[j];
+ unsigned long size;
+
+ size = PAGE_ALIGN(bm->headroom + mod[j].mod_end);
Just do
unsigned long size = PAGE_ALIGN(bm->headroom +
mod[j].mod_end);
?
yep, not sure why I even split it.
v/r,
dps
