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Lift up core size limits on some platforms. Fix potential memory

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corruption with big core on small memory systems. Document remaining
	limits.
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Vladimir 'phcoder' Serbinenko 2013-03-07 08:17:24 +01:00
parent f6b58fe538
commit 774683685f
9 changed files with 210 additions and 32 deletions
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38
docs/grub.texi
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@ -89,6 +89,7 @@ This edition documents version @value{VERSION}.
* Serial terminal:: Using GRUB via a serial line
* Vendor power-on keys:: Changing GRUB behaviour on vendor power-on keys
* Images:: GRUB image files
* Core image size limitation:: GRUB image files size limitations
* Filesystem:: Filesystem syntax and semantics
* Interface:: The menu and the command-line
* Environment:: GRUB environment variables
@ -2390,6 +2391,43 @@ In GRUB 2, images for PXE network booting are now constructed using
contains the @samp{pxe} and @samp{pxecmd} modules. @xref{Network}.
@end table
@node Core image size limitation
@chapter Core image size limitation
Heavily limited platforms:
@itemize
@item i386-pc (normal and PXE): the core image size (compressed) is limited by 458240 bytes.
kernel.img (.text + .data + .bss, uncompressed) is limited by 392704 bytes.
module size (uncompressed) + kernel.img (.text + .data, uncompressed) is limited by the size of contiguous chunk at 1M address.
@item sparc64-ieee1275: kernel.img (.text + .data + .bss) + modules + 256K (stack) + 2M (heap) is limited by space available at 0x4400. On most platforms it's just 3 or 4M since ieee1275 maps only so much.
@item i386-ieee1275: kernel.img (.text + .data + .bss) + modules is limited by memory available at 0x10000, at most 596K
@end itemize
Lightly limited platforms:
@itemize
@item i386-qemu: kernel.img (.text + .data + .bss) is limited by 392704 bytes.
(core.img would be limited by ROM size but it's unlimited on qemu
@item All EFI platforms: limited by contiguous RAM size and possibly firmware bugs
@item Coreboot and multiboot. kernel.img (.text + .data + .bss) is limited by 392704 bytes.
module size is limited by the size of contiguous chunk at 1M address.
@item mipsel-loongson (ELF), mips(el)-qemu_mips (ELF): if uncompressed:
kernel.img (.text + .data) + modules is limited by the space from 80200000 forward
if compressed:
kernel.img (.text + .data, uncompressed) + modules (uncompressed)
+ (modules + kernel.img (.text + .data)) (compressed)
+ decompressor is limited by the space from 80200000 forward
@item mipsel-loongson (Flash), mips(el)-qemu_mips (Flash): kernel.img (.text + .data) + modules is limited by the space from 80200000 forward
core.img (final) is limited by flash size (512K on yeeloong and fulooong)
@item mips-arc: if uncompressed:
kernel.img (.text + .data) is limited by the space from 8bd00000 forward
modules + dummy decompressor is limited by the space from 8bd00000 backward
if compressed:
kernel.img (.text + .data, uncompressed) is limited by the space from 8bd00000 forward
modules (uncompressed) + (modules + kernel.img (.text + .data)) (compressed, aligned to 1M)
+ 1M (decompressor + scratch space) is limited by the space from 8bd00000 backward
@item powerpc-ieee1275: kernel.img (.text + .data + .bss) + modules is limited by space available at 0x200000
@end itemize
@node Filesystem
@chapter Filesystem syntax and semantics