March 2026 - SeaBIOS - mail.coreboot.org

[PATCH] scripts: Increase BUILD_MIN_BIOSTABLE for auto-sized and 128KB ROMs
by Mike Banon March 20, 2026

March 20, 2026

[PATCH] scripts: Increase BUILD_MIN_BIOSTABLE for auto-sized and 128KB ROMs When CONFIG_ROM_SIZE is left at 0 (auto), checkrom.py will automatically determine the ROM size based on the actual binary size (up to 256KB). However, layoutrom.py only increased BUILD_MIN_BIOSTABLE to 8192 when CONFIG_ROM_SIZE was explicitly set to 256 or larger. This meant that if the code grew large enough to require a 256KB ROM, layoutrom.py would still use the smaller 2048-byte F-segment reserve, potentially causing resource allocation problems in case of a big number of boot entries. Also, 128KB ROMs should have a larger 4096-byte F-segment reserve. Fix this erroneous behavior for non-specified CONFIG_ROM_SIZE case by calculating the total raw size of all sections that will be placed in the ROM. This raw sum underestimates the final binary size by roughly 5% due to alignment padding and relocation tables, so if it exceeds 64KB we can reliably conclude the final ROM will be at least 128KB and set BUILD_MIN_BIOSTABLE = 4096; if it exceeds 128KB the final ROM will be 256KB and we set BUILD_MIN_BIOSTABLE = 8192, matching the behavior for explicitly configured 128KB and 256KB ROMs. Signed-off-by: Mike Banon <mikebdp2(a)gmail.com> --- scripts/layoutrom.py | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/scripts/layoutrom.py b/scripts/layoutrom.py index abebf021..4fe75ceb 100755 --- a/scripts/layoutrom.py +++ b/scripts/layoutrom.py @@ -651,10 +651,6 @@ def main(): # Read kconfig config file config = scanconfig(cfgfile) - # larger roms have more room in the f-segment due to moving out 32bit code - if config.get('CONFIG_ROM_SIZE') >= 256: - BUILD_MIN_BIOSTABLE = 8192 - # Figure out which sections to keep. allsections = info16[0] + info32seg[0] + info32flat[0] symbols = {'16': info16[1], '32seg': info32seg[1], '32flat': info32flat[1]} @@ -670,6 +666,20 @@ def main(): keepsections = findReachable(anchorsections, checkKeep, symbols) sections = [section for section in allsections if section in keepsections] + # larger roms have more room in the f-segment due to moving out 32bit code + if config.get('CONFIG_ROM_SIZE') >= 128: + BUILD_MIN_BIOSTABLE = 4096 + if config.get('CONFIG_ROM_SIZE') >= 256: + BUILD_MIN_BIOSTABLE = 8192 + if config.get('CONFIG_ROM_SIZE') == 0: + sections_size = 0 + for section in sections: + sections_size += section.size + if sections_size > 64 * 1024: + BUILD_MIN_BIOSTABLE = 4096 + if sections_size > 128 * 1024: + BUILD_MIN_BIOSTABLE = 8192 + # Separate 32bit flat into runtime, init, and special variable parts anchorsections = [ section for section in sections -- 2.53.0

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[PATCH] config: Raise MPTABLE and SMBIOS F‑segment size limits from 600 to 768
by Mike Banon March 19, 2026

March 19, 2026

[PATCH] config: Raise MPTABLE and SMBIOS F‑segment size limits from 600 to 768 The current 600‑byte limit for copying MPTABLE and SMBIOS tables to the F‑segment is arbitrary and not aligned with power‑of‑two sizes. Some platforms require slightly larger tables (up to ~740 bytes), causing them to be truncated. Increase the limit to 768 bytes, a rounder value that provides ample headroom while remaining within the F‑segment space. Adjust both limits together for consistency. Signed-off-by: Mike Banon <mikebdp2(a)gmail.com> --- src/config.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/config.h b/src/config.h index 16952eb7..5df753cf 100644 --- a/src/config.h +++ b/src/config.h @@ -22,9 +22,9 @@ // Largest supported externaly facing drive id #define BUILD_MAX_EXTDRIVE 16 // Number of bytes the smbios may be and still live in the f-segment -#define BUILD_MAX_SMBIOS_FSEG 600 +#define BUILD_MAX_SMBIOS_FSEG 768 // Maximum number of bytes the mptable may be and still be copied to f-segment -#define BUILD_MAX_MPTABLE_FSEG 600 +#define BUILD_MAX_MPTABLE_FSEG 768 #define BUILD_MODEL_ID 0xFC #define BUILD_SUBMODEL_ID 0x00 -- 2.53.0

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[PATCH] boot: Replace hardcoded BEV array size with BUILD_MAX_EXTDRIVE * 3
by Mike Banon March 19, 2026

March 19, 2026

[PATCH] boot: Replace hardcoded BEV array size with BUILD_MAX_EXTDRIVE * 3 The BEV array stores boot entries for floppy, HDD and CDROM drives, as well as option ROMs and other boot sources. The previous hardcoded limit of 20 entries was arbitrary and could be exceeded when many drives are present – especially with the upcoming support for multiple floppy images. The max number of drive boot entries is bounded by BUILD_MAX_EXTDRIVE per drive type. Since there are three drive types, the worst-case drive-only total is BUILD_MAX_EXTDRIVE * 3. Using this value ensures that the array cannot overflow due to drives, while still leaving room for a modest number of option ROM entries in practice. Signed-off-by: Mike Banon <mikebdp2(a)gmail.com> --- src/boot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/boot.c b/src/boot.c index 5c37dafd..18e62a43 100644 --- a/src/boot.c +++ b/src/boot.c @@ -798,7 +798,7 @@ struct bev_s { int type; u32 vector; }; -static struct bev_s BEV[20]; +static struct bev_s BEV[BUILD_MAX_EXTDRIVE * 3]; static int BEVCount; static int HaveHDBoot, HaveFDBoot; -- 2.53.0

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[PATCH] scripts: Increase BUILD_MIN_BIOSTABLE for auto-sized ROMs
by Mike Banon March 19, 2026

March 19, 2026

[PATCH] scripts: Increase BUILD_MIN_BIOSTABLE for auto-sized ROMs When CONFIG_ROM_SIZE is left at 0 (auto), checkrom.py will automatically determine the ROM size based on the actual binary size (up to 256KB). However, layoutrom.py only increased BUILD_MIN_BIOSTABLE to 8192 when CONFIG_ROM_SIZE was explicitly set to 256 or larger. This meant that if the code grew large enough to require a 256KB ROM, layoutrom.py would still use the smaller 2048‑byte F‑segment reserve, potentially causing resource allocation problems in case of a big number of boot entries. Fix this erroneous behavior for non-specified CONFIG_ROM_SIZE case by calculating the total raw size of all sections that will be placed in the ROM. This raw sum underestimates the final binary size by roughly 5% due to alignment padding and relocation tables, so if it exceeds 128KB we can reliably conclude the final ROM will be 256KB. In that case set BUILD_MIN_BIOSTABLE = 8192, matching the behavior for an explicitly configured 256KB ROM. Signed-off-by: Mike Banon <mikebdp2(a)gmail.com> --- scripts/layoutrom.py | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/scripts/layoutrom.py b/scripts/layoutrom.py index abebf021..7f33d4b4 100755 --- a/scripts/layoutrom.py +++ b/scripts/layoutrom.py @@ -651,10 +651,6 @@ def main(): # Read kconfig config file config = scanconfig(cfgfile) - # larger roms have more room in the f-segment due to moving out 32bit code - if config.get('CONFIG_ROM_SIZE') >= 256: - BUILD_MIN_BIOSTABLE = 8192 - # Figure out which sections to keep. allsections = info16[0] + info32seg[0] + info32flat[0] symbols = {'16': info16[1], '32seg': info32seg[1], '32flat': info32flat[1]} @@ -670,6 +666,16 @@ def main(): keepsections = findReachable(anchorsections, checkKeep, symbols) sections = [section for section in allsections if section in keepsections] + # larger roms have more room in the f-segment due to moving out 32bit code + if config.get('CONFIG_ROM_SIZE') >= 256: + BUILD_MIN_BIOSTABLE = 8192 + if config.get('CONFIG_ROM_SIZE') == 0: + sections_size = 0 + for section in sections: + sections_size += section.size + if sections_size > 128 * 1024: + BUILD_MIN_BIOSTABLE = 8192 + # Separate 32bit flat into runtime, init, and special variable parts anchorsections = [ section for section in sections -- 2.53.0

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